Yumi Ishiyama is the tetartagonist from the French animated television series Code Lyoko.
Yumi was born in Kyoto, Japan, although her family immigrated to France when she was just a baby. Having been raised among traditional Japanese values, she shows complete respect for her parents, sometimes even to excess. She attributes a lot of importance to her origins, being more than proud of her Japanese heritage which can be seen when she firmly states the common mistake of her being mistaken for Chinese and correcting that she is actually Japanese. She has even planed later to return to her roots.
The relationship of Yumi and Ulrich is complex and often very ambiguous since they often don't share their thoughts about each other often, even though their feelings are more than obvious throughout the course of the show. In XANA Awakens Part 1 and 2, showing how Ulrich and Yumi first met, the two can be shown to have something of a first attraction to each other which significantly grows throughout the episode. They two almost kiss in the season 1 episode Routine, after their repressed attraction and feelings come to head, but they decide to keep it a secret. Strong respect, mutual admiration and reciprocal feelings (although distant) join these two figures in a very strong relationship. They often find themselves wavering between platonic friendship and genuine romance on a regular basis throughout the show. However, in the opening of season 3, Yumi declares that they need to assume a platonic relationship status once and for all and announces that they can be just good friends, but nothing more. This clearly horrifies Ulrich but he still begrudgingly goes along with her decision without any argument. Although Yumi was the one to call this choice in their relationship, it soon becomes obvious that she as well doesn't like it. Despite this decision on both parts, it becomes clear that they still have strong feelings for each other. It is implied in the Code Lyoko season 4 finale, Echoes, that they're eventually re-exploring the romantic part of their relationship again.
In Code Lyoko: Evolution, one year after the season 4 finale, it seems as though Ulrich and Yumi have gone back to their "just good friends" status in the beginning of the season. (Although Ulrich tries to confess his love for her on multiple occasions, and has apparently given up.) But as the plot thickens, their romantic relationship, or at least their romantic attraction to each other becomes more and more apparent. She even goes as far as to (indirectly) call him her "soul mate" through an English story assignment when basing a main male character (who is the love interest of the girl character) on him in the episode Intrusion. Also in the ending of the episode, Yumi and Ulrich finally admit how much they care for each other and seemingly reconcile their blossoming romance. Later in the episode, Massacre, when Aelita asks Yumi how her relationship with Ulrich is going, Yumi admits that things are going much better since he has become more "considerate" towards her feelings, argued less with William and has become more mature than he's been in the past, making her happy.