Ryu

Ryu is first seen smoking in an otherwise empty train car, laying across the seats right below a "NO SMOKING" sign. She puts the cigarette out when Tou enters.

Ryu is the first to investigate what's going on with the train car as it is transported to the Digital World. After arriving and meeting her partner, Labramon, Ryu insists they must find Yumeto, who was separated from the group as they were transported.

Throughout the adventure, Ryu can be seen looking after the others, and is the most insistent that Tou stay with the group when they discuss splitting off. It becomes clear that the pair have some history together.

Later, after the group is halved, Tou and Ryu agree to split up to search for Yumeto and Hanesawa respectively. While looking for Hanesawa in the Dark Woods, Ryu and Labramon meet a friendly Mephismon, who needs help finding something - his Heart. In exchange for their help, Mephismon offers to guide Ryu and Labramon through the Dark Woods.

Ryu approaches the Heart, she must depend on Labramon to fend off emotion-based attacks from the Dark Woods, meant to draw out her emotions and make the heart more powerful. This leaves Ryu feeling helpless and vulnerable, and she is confronted by her own fears.

As she draws nearer to the heart, Mephismon tells Ryu how he tried to lock away his emotions, only for the Heart to become enveloped in darkness and corrupt what was once the Cloudy Woods. Ryu recognizes her own tendency to lock away and hide her emotions, and bears her feelings to the Heart - her fears, her desires, her joys, all of them. This act of sincerity frees the Heart of its corruption, allowing it to return to Mephismon. Inside the tree trunk the Heart had resided in, Ryu finds the Crest of Sincerity.

Later, when everyone finally catches up to Beelzemon and Yumeto, Ryu helps comfort Beelzemon by insisting that he has more friends in the group than just Yumeto.