Twin Signal(1996)

If you want to challenge the ultimate humanoid fighting machine, be sure to bring him some chocolate!

Twin Signal is a Japanese anime series about Signal, a powerful robot built by Dr. Otoi as a companion for his grandson Nobuhiko. A programming glitch creates an unusual problem: whenever Nobuhiko sneezes, Signal transforms from a temperamental adult into an adorable, chocolate-loving baby. Life in the Otoi household—where robots, people, and animals coexist—is generally peaceful and playful, marked only by minor squabbles over chores and the affections of the female robot Elara. That changes when Pulse, an earlier robot prototype loaded with weapons and severely nearsighted, attacks Signal on a mission to steal advanced robot technology. Reprogrammed by Dr. Otoi's mysterious rival, Pulse will destroy anyone in his path. Signal must now protect Nobuhiko while navigating his unpredictable transformations and facing a dangerous adversary.