"Seiji Utsunomiya is a main character in the Japanese manga ""How to End an Unrequited Love"". He is introduced as a handsome and popular college student who loves basketball and has a carefree personality. Seiji initially seems to be an easy-going person, often teasing others with his playful banter and flashing his charming smile.

However, as the story progresses, it becomes clear that Seiji has a deeper and more complex personality than what he shows on the surface. He is struggling with his own issues, particularly regarding his unrequited love for his childhood friend, Yuki Sato. Despite being a confident and outgoing person, Seiji finds it hard to express his feelings to Yuki, which has caused him a lot of emotional distress over the years.

Despite his struggles with love, Seiji remains a loyal and supportive friend to the protagonist, Rio Yazaki, who has also been dealing with her own unrequited love. He listens to her problems, offers advice, and is always willing to lend a helping hand. This shows that despite his own personal troubles, Seiji values his friendships deeply and knows how to be a caring and dependable person.

Throughout the story, Seiji’s character evolves significantly as he learns to open up and face his feelings for Yuki. He begins to take charge of his emotions and confronts his fears, which is a major turning point for his character development. Through his journey, Seiji serves as a relatable character for readers who have also struggled with unrequited love and the challenges that come with it.

In conclusion, Seiji Utsunomiya is a well-crafted character in ""How to End an Unrequited Love"" who embodies both the struggles and triumphs of navigating unrequited love. His charming personality, loyalty, and growth throughout the story make him a memorable and relatable character that draws readers in."