Kazuki Mizuhara

Kazuki Mizuhara is a student of Shishido Academy and roommate of protagonist Tomu Shirasagi.

Appearance
Kazuki is a teenager of medium build and height. He sports a thick pair of optical lenses. Over the course of the story, however, Mizuhara's height had shrunken drastically, his full height barely passingTomu's waistline.

Kazuki's most prominent feature is his distinctive 'mushroom' haircut, which has earned him the nickname 'Mizuhara Mushroom' from the other students. This nickname spread to the point that seemingly all the students believed it to be his real name, causing them to express surprise when he revealed it to be otherwise.

Shishidō Entrance arc
Kazuki first appears after being called to the Headmaster's office. He is introduced to Tomu Shirasagi by Satō, who tells the former that Kazuki is the class representative and the two of them will be roommates, so he can ask any questions. The two students take a walk to the dorms after their business is finished. Kazuki introduces himself and asks Tomu if it's his first time in Tokyo, to which the latter replies that he was born there and simply moved around a lot. Kazuki tells him that since he's a transfer student, people may look at him strangely, but that he shouldn't worry about it. Kazuki tells him they're all good people as Tomu does express worry, but is soon caught off guard as Tomu tells him that he's worried about whether he can get the fish into his net.

In class, Tomu introduces himself in front of everyone. As he does so, Kazuki gets a strange feeling, as if the atmosphere of the room was changing. At the end of the class, Kazuki asks Tomu what he thought, after which he takes him to the cafeteria. While there, Tomu expresses his surprise at the curriculum of Shishidō Academy. Kazuki explains that the school is above the normal level and one can even take classes in French or German if they desire. As Tomu comments on the pride of a student, Kazuki asks if he's not proud to have come, to which the former explains the he didn't really care where he went and it was his parent's idea. As Tomu mentions his net again, Kazuki asks what he means given the lack of a fishing club.

Suddenly, Mika Shishidō arrives with her group, and Kazuki explains that she's a third year student, the headmaster's great-granddaughter and is known as the Rose of Shishidō Academy. When Tomu goes up to her and claims to have something nobody will ever see, Kazuki grows worried as he takes out a boiled egg, afraid that he'll make a fool of himself. Once he eats it and claims it will never be seen again, Mika walks away, angry at him.

Inside their classroom, Kazuki confronts Tomu over his antic, stating that if anything had happened, as class representative, he would be responsible. Tomu claims he had a reason, that he was doing it to lay out his net. Kazuki asks if Mika was the fish but Tomu replies that she was actually the bait. Suddenly, Aoto arrives to confront Tomu. Kazuki reveals he's the head of the Public Morals Committee and tells Tomu not to go against him. However, Tomu does not listen and instead prepares a game, to Kazuki's worry. Aoto replies that they can play his card game, but they must use 20 cards rather than 10, shocking Kazuki. The two then leave for another room where Kazuki chastises Tomu's decision. However, Tomu does not regret anything and insists he will win, as Kazuki notes that the atmosphere of the room changed.

Kazuki later guides a blindfolded Tomu back into the classroom and prepares the game for him. After going through the format, Kazuki wonders how Tomu will win, believing it to be impossible. Tomu then whispers something in Kazuki's ear, causing him to shout out that Tomu is correct. With that, Tomu wins the game by identifying Aoto's hiding spot in a clock. However, Tomu also points out that Aoto never listed the clock as a potential spot, meaning he cheated. Kazuki is then asked by Aoto what Tomu said to him, making him reveal that he pointed out one of them left their zippers unzipped. Tomu reveals his trick, astounding everyone. However, Kazuki asks what he'd have done if Aoto was truthful, with Tomu answering that that would've been easier. Tomu reveals he will double the value of each game, causing Kazuki to exclaim that he'll reach enormous figures quickly that way.

Mizuhara was initially suspicious of Natsumi when she approached Tomu, thinking she was in cahoots with Yuka after the card incident. He was also quite nervous when Tomu had prepared a chainsaw for his blackjack match against Yuka, hoping it will not be used. After tomu's victory, Mizuhara and Natsumi took him to the hospital to get his finger reattached and made sure to visit him every chance they got. He also greatly admired how Tomu not just won the gamble, but had also unintentionally got Yuka to fall for him, too (much to Natsumi's chagrin).

Mizuhara and Natsumi would then assist Tomu in his billiards training with hustler Gokijima. In Tomu's pool table match with Rio Asahina, Mizuhara served as his aid, where he became a vital part of helping Tomu win despite the numerous unexpected backfires planned out beforehand. In the final round, Mizuhara, along with Natsumi and Tomu himself managed to rearrange the positions of the pool balls without anyone noticing (save for Abidani himself), allowing him victory in an otherwise hopeless scenario.

In the dice battle, Mizuhara was made an unwilling contestant by Yoshio, who chose to challenge him in dice stacking despite only being the MC for the matches. Mizuhara was scared out of his mind as not only was he an amateur, but the loser will be slashed in the butt numerous times with a switchblade. He managed to get himself a few practice minutes after humiliating himself, then thanks to a little subtle hints from Tomu, he managed to win by stacking two horizontal dice on the stack.

During the Flag capture game, Mizuhara declines taking part as it was just too scary for him. Instead, he served as the sideline help for Tomu's team. He was also given intruction from Tomu should anything happen, he will come by piloting a blimp to get them off the mountain.

Mizuhara goes to the springs hotel with Tomu, Natsumi, and Yuka to meet up with Mayo, where they learn of the history of Abidani and the Class Reunion.He is basically forecd to come along to Macau City, ruining his summer plans of playing online games. When Tomu gets hospitalized, he suggests to Natsumi, Yuka, and Rio that it was now up to them to raise the 1 billion yen entry fee for Tomu in his place. While the girls had lost all their money, Mizuhara managed to make up for their losses in the poker room, revealing his skill at poker. He had managed to win 800 million yen with consecutive victories. It was then revealed to all by Akira Juumonji that Mizuhara had n online personality, "Kaizer Mizuhara", who was the top ranking online strip poker player. Mizuhara is challenged by Juumonji to a game of Perfect Poker, 800 million yen on the line.

Skills
Mizuhara had later been revealed to be an expert poker player. How he gained this skill was from playing numerous online strip poker games under the alias "Kaizer Mizuhara". Due to his drive to see naked girls, he became infamous on the online poker community, earning the name "Stripping Emperor".