Seiji Amasawa (天沢 聖司 Amasawa Seiji) is a character from Whisper of the Heart. He is a boy around 14 to 15 years old and a violin player attending the same school as Shizuku Tsukishima. He spends his time making violins in the workshop below his grandfather's antique shop where they do violin making classes. Seiji also attends the same school as Shizuku Tsukishima, they are in the same grade but in different classes. In the English version, Seiji was voiced by David Gallagher and Issei Takahashi in the Japanese.
Seiji has short, dark hair and white skin. His eyebrows are brown and his eyes are dark, the same black/brown color of his hair. His face is long and his forehead is wide, his chin ending with a point.
Seiji is a confident young man who has been in love with Shizuku for most of their school lives. When they first encounter each other Shizuku perceives him as rude, and refers to him as "stupid jerk" which she repeats numerous times, however as the film progresses we see that he is a very sensitive and loving person, and his affection for Shizuku become very apparent, especially at the end of the film. He is very driven, wanting to go to Italy on his own to perfect the art of violin making, and willing to leave everything behind, showing both his confidence and his abilities.
Seiji has a close relationship with his grandfather who owns the antique shop, and who is supportive of his dream to make violins, unlike his parents.
He also develops a close relationship with Shizuku, at the end telling her that he is in love with her and can see them getting married.
Because the film is from Shizuku's point of view, these are the only two relationships properly explored in terms of Seiji in the film. We do not know who his friends are, because he is in a separate class to her.
He is a talented violinist and an aspiring violin maker, the skill which he wishes to develop in Italy and is told he has "the potential to be great."
We must be meant for each other, Shizuku.
- —Seiji to Shizuku Tsukishima