Ren Kisaragi, known as Round, is a lighthearted and energetic individual. He exhibits a playful, affectionate demeanor towards Arisa, treating her like a younger sibling while simultaneously claiming she will be his future wife. This enthusiasm drives him to persistently initiate physical gestures like hugs, which often provoke negative reactions from Arisa, including slaps. He consistently responds with laughter and smiles, showing no offense.

Within the Wonderland setting, he embodies the Dormouse, displaying clingy and childish tendencies. His primary interests revolve around sleeping and playing games with Arisa, though he clearly prefers the latter. His Wonderland form features mouse-like traits such as ears and a tail. During one incident, Arisa rescues him from a pot by pulling his tail, demonstrating his vulnerability in this state.

Ren maintains an optimistic outlook, consistently seeing good in others regardless of their actions. This includes retaining a positive view of Chrono due to their prior friendship. He serves as a source of lightheartedness, prioritizing fun and enjoyment. This philosophy is evident in his statement that satisfaction comes from ensuring experiences are engaging enough to stay awake.