Kaeru Idochū is a character from the Duel Masters VS anime, identifiable by his distinctive speech patterns and unique visual traits. He refers to himself using the first-person pronoun Wai and often ends his sentences with the frog-like verbal tic kero. His design incorporates frog motifs, including two small, living frogs that he keeps on his person, one perched on his head and another on his crotch. These frogs are capable of changing their expressions and moving independently.

Initially, Idochū is introduced as a classmate of the shy and unassuming girl named Sasori. Observing her failed confession to Kojirō, he takes the initiative to advise her. His suggestion is not born of pure kindness; his original intention was to manipulate the timid Sasori for his own amusement. He proposed a dramatic makeover, complete with flashy fashion and a bold new attitude, as a way to transform her. This plan backfires considerably. After Sasori adopts her new, confident persona, their dynamic completely reverses. Idochū finds himself subservient to her, respectfully calling her Ojou (young lady) and acting as her loyal underling. This transformation appeals greatly to his personal tastes, and he frequently reacts to her with visible delight, his eyes turning into hearts as he joyfully hops around.

Throughout the main narrative of Duel Masters VS, Idochū does not participate in any depicted Duel Masters matches. His role is primarily that of a supporting character in Sasori's arc, though the ending theme animation briefly shows him engaging in a duel with her. His development is closely tied to Sasori, illustrating a clear shift from a would-be manipulator to a devoted follower. Despite not dueling, he appears to be a popular figure; a later sequel series, Duel Masters VSR, features an in-universe video site ranking where he holds the third position in popularity. He continues to make cameo appearances in subsequent series, such as Duel Masters VSR and VSRF, with a speaking role in VSRF as an assistant director. Aside from his loyal service to Sasori, no other significant relationships are documented.