Yuu as seen in the manga.
|Manga Debut||Chapter 1|
|Anime Debut||Episode 1|
Yuu Matsuura (松浦 遊 Matsuura Yū) is the male protagonist of the series. Miki gives him the "Marmalade Boy" moniker as she thinks that he is like marmalade - pretty looking, and sweet only on the surface, yet bitter. Compared to Miki, Yuu's character is almost a complete opposite to hers, as he tends to be more detached, less emotional, and less open about his feelings. He admits to admiring Miki's ability to show her emotions clearly, and it being one of the reasons he fell in love with her. Yuu is smart and naturally athletic, being able to excel in almost every sport although he did not join any clubs in order to focus on his studies. Yuu's dream is to become an architect and in the anime he leaves to attend St. Andrews high school near New York City to study it there. Yuu teases Miki a lot, but this is his way of showing affection for her. His first kiss with Miki is a complete surprise for her because she had only met him a few days prior at an introductory dinner attended by both their families. The Marmalade Boy Movie, which is a prequel to the TV series and set a few days before this dinner, reveals that Yuu fell in love with Miki before they actually met. It shows that he saw Miki when she was out and followed her, witnessing her interactions with the Gastman Team, all without her knowledge.
One of Yuu's biggest goals, in addition of being an architect, is to uncover his paternity. A series of unfortunate events leads him to believe that Youji is not his biological father. Nobody knows of his quest at first, especially Miki, as he researches various individuals who may or may not have fathered him, acculumating with him believing that Jin is his father, and Miki to be his half-sister. However, it is revealed that Youji is his true father and is free to continue his and Miki's relationship. At the end of the anime, they marry; in the manga, they are making plans to marry after college.