- "Hi, my name's Yu, I come from the nearby town, but I like to play here a lot."
- — Yu, Doubutsu no Mori (film)
Yu (ゆう, Yū) is one of the main characters in Doubutsu no Mori (film), being the only male human. Yu changes his outfit daily; throughout the film, he dressed as a ninja, a pirate, in camouflage, and as a snow bunny. He seems to be a reference on how in the Animal Crossing series games, a person could connect through Wi-Fi, so players from other towns can come visit their town. He does not live in Animal Village, but visits often. He loves to play with Alfonso by competing for collectibles such as fossils and bugs.
Ai and Yu first meet when Ai is delivering a package. Yu is having a bug catching contest with Alfonzo, and stumbles into Ai. Later, a bug crawls on to Ai in the forest. Yu catches the bug on Ai and thanks her, giving her another bug in return. Ai, freaked out by the bug Yu gave him, screams. Later, Ai sees Yu and Alfonzo digging for fossils. While Yu and Alfonzo are doing this, Resetti pops out of the ground, and lectures Yu and Alfonzo for destroying his tunnel. Shortly after Margie moves away, Ai falls into one of Yu and Alfonzo's pitfalls. Yu and Alfonzo laugh, but Ai, still depressed, gets herself out of the pitfall and walks away, leaving Yu and Alfonzo surprised. Later on, when Yu and Alfonzo complete their fossil collection, Rosie remarks that there is a much more resourceful cave nearby. This leads Ai, Yu, Rosie, Margie and Alfonzo on a big adventure to find the cave. Later, the group discovers the cave. They find a giant fossil called the Seisamasaurus, and Yu risks his life to climb up to the top of it, despite the group's warning. This causes the cave to collapse. The group, now conscious, wakes up and sees a U.F.O, which crashes back at Animal Village, where the Miracle festival is taking place. Yu and the group arrive at the town, and search for the lost pieces of the U.F.O. Yu and the group find the missing piece of the U.F.O, which turns out to be an alien. To thank Ai and the group for finding it, it shape shifts into Ai. The Miracle festival ends, with everyone happy and well.
- Yu and Ai's names might be a pun on the English words "you and I."
- Yu's voice actress, Yū Kobayashi, shares his name.