Willumi

Willumi is the ship between Code Lyoko characters William Dunbar and Yumi Ishiyama.

Canon
William met Yumi when arriving to Kadic academy as a new studend, and quickly took an interest on her, and when partened together for a school field trip, they talked about love and William mentioned it drove him crazy, which made Yumi blush, (much to Ulrich's jealousy).

They become friends and often ate lunch together.

In Valentine's day, William gave Yumi a bouquet of roses and she thanked him and kissed him on the cheek, making William blush (unaware she did that to get back at Ulrich for writing a love poem to Sissi).

In a swimming class, William did a dive to impress Yumi and she clapped for him.

One night, after Yumi returned home from a Lyoko mission, she found William outside waiting for her and told her about his feelings and tried to kiss her but she rejected him and William knew it was for Ulrich, and the next day he got in an argument with him and fought, sending both guys to detention.

In a end of the year party, William asked Yumi out but she declined.

Time passed and Yumi became annoyed with William's flirting and stalking her and told him to leave her alone, which angered him and led to discover the Factory and the Supercomputer, however while facing a Xanafied bomb worker, William fought him to protect Yumi and she warned him against that. Later after he managed to deactivate a bomb and save the factory from being blown up. William asked to join their group and everyone voted and there was one "No", which William angrily assumed to from be Ulrich and left, however it came from Yumi, who seeing William outside her house apologized but said she doesn't think he could be trusted.

However, after XANA managed to destroy all four Lyoko sectors, Yumi finally allowed him to join but warned him that XANA was dangerous. And when William was possessed by XANA on his first mission for his inmaturity, Yumi fought him and soon was quickly devirtualized by him with her telling him that she always knew it was a bad idea to let him join them. And after XANA-William destroyed Lyoko, Yumi became concerned he could be gone.

But soon she found that William was still alive but under XANA's control and became his main general. Which forced them to create a clone of William to cover up his absence on the school.

When Jeremie created new Lyoko Avatars for the others, XANA-William approached her and flirted with her before pushing her to the Digital Sea, and Yumi in retaliation pulls him with her.

One day, when fighting William alone in the Ice Sector, XANA-William had her disarmed and was about to devirtualize her, but Yumi pleaded with him, reminding him he swore to be a Lyoko Warrior, her words reached William and he soon was in an internal battle to regain control of his body, and a concerned Yumi approached him and tried to help him and reached to touch his cheek, but he (still under XANA's control), kicked her and fought her again, only to be defeated by Aelita, who was told by a saddened Yumi that by one second the real William came back, giving her hope of freeing him from XANA someday.

When Sissi became suspicious of William's clone behavior, Yumi distracted her with a lie about her dating William, while hugging the clone and later to get away from Sissi, she pretended by calling him "her boyfriend" and took him for a walk.

After freeing William from XANA, Yumi and Ulrich happily greeted him and helped him to stand up. Later when he was talking with his parents, he waved at Yumi and she smiled and waved back at him.

However, Yumi agreed with the others to be civil with William but not to allow him to be in Lyoko again. But he soon became possesed by XANA again in the real world and fought Yumi and Ulrich, and only became free when Jeremie's program destroyed XANA for good.

On the day the Lyoko Warriors were to shut down the Supercomputer, William discreetly asked Yumi if they shut it down, but Yumi replied they didn't yet as her friends were still nolstalgic, but she was hopeful for the future, and William told her he too and took her hands, but Yumi replied "Except when it's a lost cause, so long Romeo" and walked away.