"Mizushima Shu is a key character in the Japanese manga ""Miss Delinquent"". He is an interesting and complex young man who plays a central role in the story, and his actions and motivations are frequently explored throughout the series.

Mizushima Shu is first introduced as a tough and aloof delinquent who attends the same high school as the manga's protagonist, Otsuji Kanade. He has a reputation for being a fighter and is feared by many of his classmates, but as the series progresses, it becomes clear that there is much more to him than meets the eye.

Despite his tough exterior, Mizushima is actually quite a sensitive and compassionate person. He is deeply devoted to his younger brother, Kouta, and is willing to go to great lengths to protect him. This sense of loyalty extends to his relationships with his friends, and we see him put himself in harm's way several times to help those closest to him.

Mizushima is also extremely intelligent and has a talent for martial arts. He is often able to anticipate his opponents' moves and use their own strength against them. This skill becomes especially important later in the series when he finds himself in several dangerous situations.

Perhaps most intriguingly, Mizushima also has a complicated past that is slowly revealed as the story progresses. It is hinted that he may have been involved in some shady dealings with a local gang in the past, and his relationship with Otsuji becomes increasingly complicated as their connections to this gang are explored.

Overall, Mizushima Shu is a fascinating and multi-dimensional character that captivates readers with his complex motivations and compelling personality. Whether he is fighting to protect his brother or navigating complicated relationships with his friends, he is a central figure in ""Miss Delinquent"" and one that readers can't help but root for."