|Occupation||Head of Intelligence Unit|
|Base of Operations||Night Troop Headquarters|
Kei Sazanami (細波計, Sazanami Kei) is the leader of Night Troop's Intelligence Unit. He is the number three man in the Night Troop, having helped Masamori Sumimura create it. However, Yomi Kasuga has shared evidence with Masamori proving that Sazanami has given intelligence on Night Troop to Kokuboro.
Sazanami usually has an outwardly friendly, disarming persona (part of why he is so good at collecting information), but is actually very cautious about every choice he makes. Because he can read minds, he usually has a very good idea of what people think of him, and is rarely ever caught unaware. Sazanami was seriously considering leaving the Night Troop, until Masamori confronted him and intimidated him into staying. Sazanami has taken Sen Kagemiya under his wing, and appears to be closest to him, though there is a great deal that even Sen does not know about him.
Sazanami was one of the founding members of the Night Troops, and is considered the number three man of the group (likely behind only Masamori and Miki Hatori).
Return of the Traitor
Kei Sazanami, leader of the Night Troop's Intelligence Unit, returns to Night Troop Headquarters after a long journey, and is greeted warmly by everyone, especially the children, who crowd around him. Makio comes out to greet him, and the kids invite Sazanami to play with them, but he claims to be tired and says he'll play later. Instead, the kids demand presents, so he gives them a new ball from his pack. For his older comrades, he has brought adult DVDs. Miki Hatori also welcomes Sazanami, and tells him that Masamori will return later that day. Afterward, Sen Kagemiya excitedly welcomes Sazanami home.
At a meeting with Masamori, Yomi Kasuga is surprised that he recalled Sazanami, and Masamori says her own position will be changing as well. Yomi notes that thanks to Masamori leaving Sazanami unchecked, Kokuboro was able to take advantage of them, and that Masamori can't deny that his friends died for him in the past. She wonders why Masamori would decide to settle things with a traitor after all this time, but Masamori doesn't give her a straight answer.
Sazanami asks how Sen's training has been going, and Sen assures him that he's been practicing. Sazanami decides that it's time for them to train together. 
The Art of Mind-Reading
Sen and Sazanami walk through a forest, discussing mind reading. Sazanami assumes that Sen hasn't been practicing on anyone, and tells him to work on developing a better poker face. Sazanami warns Sen to be careful when training around the rest of the Night Troop, as he might give away his true intentions. However, he is satisfied that each of them has convincing camouflage: Sen is a receptive person with sharp senses, and Sazanami is talented at hypnosis and brainwashing. Kei is confident that no one suspects that they can both actually read what lies in the depths of people's minds. Sen admits that he has practiced reading the minds of random strangers, but he could only read surface thoughts that would be easily guessed simply by looking at their faces, and that anything he picked up would still be in jumbled bits and pieces. Sazanami stresses that this is why he must practice: to be able to screen out unimportant information and obtain the important information. He adds that they also can't read everything, so it is important to be able to fill in the rest with their own deductive skills.
They spot a troubled woman nearby, and Sazanami decides they will practice on her. They move closer because the range of Sazanami's mind reading is about ten meters. Sen has reached as far as about fifty meters during training, and thinks he can expand it even further if needed. He admits that demons are easier, but humans are difficult to read. Sazanami tells Sen to start, and moves to a bench closer to the woman so she is within his range. Sen watches as Sazanami quickly and easily begins reading the woman's mind, and is so impressed that he nearly forgets he is supposed to be doing the same. After Sen takes his turn, they return to the forest to compare results. Sen picked up two images: meat and potato stew, and sweet and sour pork. He guesses that she was trying to decide what to make for dinner that night. Sen also saw a middle-aged man, and guesses that they are married, but that there is some distance between them. He is unable to guess what was bothered her, since he focused on the food. Sen notes that the stew seemed burnt but that the woman felt positive about it, while the pork was well-made, but she felt negative about it. Kei fills in the blanks: the woman's husband is returning from a far-away job, and she wants to make a dinner that he likes. However, she is bad at cooking, and while the stew is what she makes best, the pork is store-bought and re-heatable.
Sazanami tells Sen to keep practicing, but warns him not to do it around Masamori, because Kekkaishi are very attuned to anything odd happening around them. He admits that other than fellow mind readers, Masamori is the only person that has been able to truly sense his abilities. Sen wonders about Yoshimori, and worries he has already revealed too much around him. Sazanami tells Sen not to hate his timid nature, because being cautious is what keeps them alive. He warns Sen that no one trusts a person who can read their hearts, and that alone, people like them are nothing. This makes Sen wonder why Sazanami leaked information on the Night Troop to enemies, and worries that Masamori has called Sazanami back to settle the matter. Sazanami admits this is correct, but isn't worried because he has made several outside contacts. He says Masamori is too young and soft to deal with him properly. Sen is alarmed when he realizes that Sazanami is planning to leave the Night Troop, and Sazanami invites him to come along, since it will give Sen more chances to improve his powers. Sazanami admits that while his position in the Night Troop is comfortable, he can't stand working under a man he can't read at all.
Sazanami goes to meet with Masamori, but the moment he opens the door to the room where Masamori and Kurohime are waiting for him, he is struck by the amount of powerful malice he senses. Masamori admits that Sazanami has been a great help to him in founding the Night Troop, but asks him directly if he is an enemy. Sazanami begins to panic. Meanwhile, Sen seriously considers Sazanami's offer, and wonders if it will really allow him to improve. Some time later, Sen tries to accept the offer. To his surprise, Sazanami says things had changed and that he'd be staying after all. He also said that he put in a good word for Sen with Masamori. Later, on Sazanami's recommendation, Masamori assigns Sen a mission to officially investigate Karasmori, but to actually investigate the people Karasumori has chosen: Yoshimori and Tokine.
While on assignment in Karasumori, Sen calls Sazanami. He describes what an irritating target Yoshimori is to follow around, and that he doesn't feel motivated to complete the job. Sazanami advises him not to give up so soon, and to get rid of his guilty conscience so he can complete the job. Sen agrees to try, and asks that Sazanami continues to guide him.
Chance at Redemption
Masamori summons Sazanami, who had been confined to headquarters and stripped of his position. Masamori offers him a mission, with a chance to be reinstated as Intelligence Unit Head. Masamori orders him to investigate the entire Ougi Clan, which Sazanami considers a test of his loyalty. Masamori asks Sazanmi to give him something he can use to destroy them.
Masamori urges Sazanami to speed up his investigation, telling him that the Ougi Clan is most likely responsible for the three men they lost in the battle with the Bear Deity. Sazanami says he was approached by Okuni's subordinates and offered an exchange of information. However, they desire details on Kekkaishi abilities, especially Masamori's mother. Sazanami understands why Masamori is hesitant, but notes that Okuni prefers to remain neutral and likely could answer any questions they had. Masamori tells Sazanami to set up the exchange.
Sen Kagemiya calls Sazanami in the hopes of discovering where Yoshimori has gone. Sazanami is purposely vague, only saying that Masamori disappeared around the same time.
In a phone conversation with Sazanami, Sen Kagemiya expresses his concerns with the Prosecution Office reacting so quickly and decisively. Sazanami thinks Sen is too involved, but agrees that it is worrying. He mentions that it isn't uncommon for people taken by them to simply vanish because it is such a confined place, which alarms Sen. Sazanami suggests that they get Tokine back as soon as possible.
Okuni asks Masamori to reward Sazanami for assisting in obtaining information on the Ougi Clan.
Investigating the Shadow Organization
Sen Kagemiya calls Sazanami to confirm his suspicion of Souji Hiura being Okuni's killer. Sazanami says he can't confirm that, since Okuni's subordinates are shutting out all outsiders, but eventually admits what he does know: that Ichirou was killed by his youngest brother, Shichirou Ougi, the next Ougi clan head. Sazanami says that Shichirou is such a powerful opponent that he has nothing to fear from anyone, and they should be careful about engaging him. Sazanami also says that Serpent's Eye, the prophetic group related to the Shadow Organization, has suffered a major leak and been dismantled.
Masamori Sumimura calls Sazanami for information. Sazanami has nothing on Konozuka Kihei, but believes the Ougi Clan was hired to kill Ichirou Ougi, and that the order was passed from the clan head to Shichirou Ougi.
Yoshimori and Sen Kagemiya wait anxiously as Sazanami finishes his interrogation of Souji Hiura. Sen asks if Sazanami was able to get any info out of Souji on the Commander, but Sazanami was only able to get bits and pieces.
At Night Troop Headquarters, Sazanami reports that after reading Souji Hiura's mind, he found all information related to the Commander blocked. Sazanami describes it as a gatekeeper present in Souji's mind, that keeps others from accessing it. Sazanami explains that a psychic typically channels their power into a specific form to more easily control it. Masamori recalls that Yumeji Hisaomi used a kind of starfish, though Sazanami likens it more to a combination of a starfish and a spider, adding that power in the form of a living being is easier to handle. He describes the Commander's psychic avatar as a sea serpent capable of residing in a person's mind. Sazanami mentions that the boy Kekkaishi used in the Karasumori Assault, despite being controlled by Yumeji, was unaware when his control was removed, and only had very vague memories. Souji, on the other hand, had no memories beyond 4-5 years ago, meaning that the majority of his memories were made up of the time he spent at the Sumimura Home. Sazanami adds that the only information related to the Commander in Souji's mind was a girl called Suigetsu, who took care of Souji. He is able to determine that she is a log-keeper, a person whose eyes and mind were restructured to store information, virtually making them human databanks. Because each department in the Shadow Organization had at least one log-keeper, Sazanami suggests that if they can find out which one Suigetsu worked for, they can also find the Commander's location.
After gathering all of the Shadow Organization's log keepers, Masamori Sumimura attempts to reassure them of their safety, explaining that he wants to interview them. Sazanami observes in secret, noting there are around 20 in all. He is approached by one of Okuni's subordinates, who reveals that she is a fellow psychic there to assist. After displaying her psychic avatar (a school of small fish), she reveals her face and introduces herself as Kisana. She and Sazanami observe Masamori's interviews, unknown to the log-keepers. When Saikaku Enjouji is interviewed, he agrees to cooperate if Masamori can guarantee their safety. He already correctly suspects that Masamori wants to know about the log-keepers' master.
After Saikaku's interview, Masamori meets with Kisana and Sazanami to discuss their findings. Sazanami confirms that the masked person controlling the log-keepers had the same psychic avatar as Yumeji Hisaomi and so must have been him. In addition, the log-keepers' eyes were modified to omit the master's face, and the information could only be obtained by a powerful psychic. Sazanami strongly suspects that Suigetsu was the girl that often accompanied Yumeji at these times. Kisana suggests that Suigetsu may hold records on all the log-keepers, effectively making her the chief log-keeper. Sazanami confirms that Suigetsu was with the Commander in Souji Hiura's memories, meaning she would likely hold the entire history of the Shadow Organization. 
Power & Abilities
Psychic Powers: Sazanami is an accomplished psychic, but lacks a psychic avatar for some reason. The only talents he openly claims to have are hypnosis and brainwashing, and only Sen and Masamori appear to be aware of what his true talent is.
- Mind Reading: Sazanami is a skilled mind reader, able to screen out unimportant information and focus on important facts in a person's mind, and fill in what he does not see with deductive reasoning. He states that he must be within about ten meters of a person to accomplish this. He admits that he is unable to read Masamori's mind at all.
- Though Sazanami is never mentioned by name in the anime, Yomi informs Masamori that his number three man leaked the news of his appointment to the Council of Twelve. Masamori corrects her and says it is inaccurate to call that person his. Masamori further indicates that he already knew this, which may imply that he was merely evaluating Yomi's investigation skills.
- In the name Sazanami Kei, 'Saza' (細) means fine, 'Nami' (波) means wave, and 'Kei' means plan.
|Night Troop (Shadow Organization Task Force)|
|Leaders||Masamori Sumimura • Miki Hatori|
|Unit Heads||Makio • Kei Sazanami • Fumiya Somegi • Kikusui • Mukade • Aikawa • Atora Hanashima|
|Subordinates||Yukimasa • Gen Shishio • Hakudo • Odo • Dai Yaegashi • Todoroki • Takemitsu • Mother and Spirit Baby • Shoki • Shu Akitsu • Sen Kagemiya • Kyoichi Hiba • Hakota • Hakota's Mother • Ito Orihara • Shiragiku • Higurashi • Yomi Kasuga • Souji Hiura|
|Ayakashi||Raizo • Yaichi and Tsukinojou|
|Trainees||Misao • Akira • En • Haruka|