Manabe has sharp, slightly long hair. There are colour drawings of Manabe have silver, grey hair and golden amber eyes. He is tall and thin but strong enough to carry Tsubasa.
We do not know much about Manabe, despite his being one of the main characters, due to the fact that he is so quiet and suspiscious. His grades and attendance are not partciularly great, though they improved due to his slight friendship with Arisa, and when he teamed up with Tsubasa he seemed to attend school more often. Despite his grades, and though not being directly stated, Manabe seems to be very intelligent. He can figure out the King's moves and motives quite easily and often realizes things that Tsubasa fails to see. He is very much an introvert, though he does get angry at times, and he does not trust others very easily. However, he is very loyal to those he cares about, and he is always there for them. He is seen as very blunt at times, and it is implied that he might have a soft side, though so far that has not been shown very much.
Manabe's relationship with Arisa has not been explored in much detail, but we do know that Arisa would often worry because he missed school and go to his apartment to bring him notes and other sorts of information. She helped him with school and accepted him despite his reputation as the problem child of Class 2B. Despite his seemingly good friendship - if you could call it that - with Arisa, it is shown in the first volume that Manabe suspected Arisa of being the King, showing that despite her seemingly kind actions towards him, he still did not trust her. Manabe was one of the few people of Class 2B that realized there had been a change in Arisa, when Tsubasa was pretending to be Arisa, so we can assume that Manabe knew Arisa quite well. It is said he used to have romantic feelings for Arisa, but after Shizuka's suicide attempt, he lost all thoughts of such things.
Manabe's relationship with Tsubasa, and most other characters, is quite complex. At first, Manabe suspected Arisa (who was really Tsubasa dressed as Arisa) of being the King, and was planning on confronting her about it. When he realized Arisa was really Tsubasa wearing a wig, the two teamed up to find the true King, becoming official allies. During the time period where they are allies, they become somewhat friends, though not in the normal aspect of the word. They trust each other more than they trust others and are able to naturally speak to each other, though no romantic relations are shown, except that Manabe seems to develop a sort of soft spot and loyalty towards Tsubasa that goes beyond what a normal alliance calls for. Their solid alliance and budding friendship comes to a halt when Tsubasa discovers that Manabe is actually in another alliance with his long time friend Shizuka Mochidzuki. Tsubasa then questions the honesty of their alliance, seeing as how at the time, Tsubasa suspected Shizuka of being the King. Shizuka also had a long time wish to get revenge on Arisa and those of Class 2B, which is why Shizuka wanted to acquire all the cell phones that correspond to the five chosen passwords of the King - so she could make a wish for revenge, and have it granted for sure, since she possessed the only phones capable of making wishes. When Manabe stole all the cell phone's Tsubasa has collected in order to find the king, this made Tsubasa question whose side Manabe was truly on. When she realized he had given the phones to Shizuka, who Tsubasa suspected of being the King, Tsubasa stopped trusting Manabe and their friendship seemed to take a backseat. When he took the phones, Manabe also stated that she trusted too easily.
Even though he seemingly betrayed Tsubasa, he continues to help her and he is never cruel or cold towards her. He never does anything mean or hurtful during the time that Tsubasa and his alliance seems to have been over. When Shizuka's wish to destroy the thing most important to Arisa is granted, Tsubasa goes out looking for Midori, Arisa's boyfriend, thinking he is the most important thing. Instead, she falls for a trap set by the king and falls into a cold, dark hole that seems impossible to climb out of. Back at the camp, where the rest of Class 2B is worried about Arisa and waiting on her so they can have dinner, Manabe realizes that Tsubasa must be the most important thing to Arisa, and despite the fact that he is allies with Shizuka, he defies Shizuka and goes to save Tsubasa. Together, they escape, and he carries her back to the camp, where they warm up by a heater, and he tells her the story of how he and Shizuka became such close friends, and why he will never betray Shizuka. At this point, it seems that Manabe is still in Shizuka's side, but this issue is not adressed until later, when Tsubasa attempts to befriend Shizuka to find out if she truly is the King and to try and get Shizuka to stop hating and seeking revenge on Arisa. During a BBQ, Tsubasa accidentally falls off a cliff, and it is Manabe who saves her. Manabe is then abscent for a few chapters, but is later seen trying to hack into Arisa's chats with a person named K, and the two are also drawn working together once again. This shows that they are back in an alliance together. Their relationship returns to being a solid alliance and a casual friendship, and Manabe then becomes abscent from the story for a while, making small cameo appearance once in a while. They have a long history and not much can be officially said about their relationship, except that they are in an alliance. It is also implied that Manabe has some sort of feelings - whether it is romantic or not is unknown - apart from the alliance for Tsubasa, since he saved her even though it would technically betray Shizuka's wishes.
Shizuka and Manabe are childhood friends. Shizuka and Manabe met at the hospital when they were very little, and he is very close and protective of her. He said she used to be a kind, happy, optimistic lady, until her parents died and she felt that everyone hated and abandoned her. He then promised Shizuka to always stay by her side, no matter what - a promise she would never forget. When Shizuka started competing to be ranked #1 in the class in order to make her Aunt, who is and was her current guardian, proud, Manabe encouraged her very much. Then, when Shizuka always lost to Arisa, he stole Arisa's notes and copied them down for her. He protected and stayed by Shizuka's side during all the hard times in her life, and he stole the cell phones from Tsubasa and gave them to Shizuka. He always helps Shizuka calm down and cares about her a lot. He can be found pushing her wheelchair lots of times. When Shizuka "betrayed" the King and was shunned by her class - even though she never had many friends before - Manabe always stayed by her side. His loyalty for her and his love for her is very deep and strong, though romantic feelings have not been explored or implied. He did betray Shizuka once or twice in order to save and help Tsubasa. When Shizuka attempted suicide, apparently thanks to the King (who was believed to be Arisa), he immideatly stopped feeling anything towards Arisa.