Sumomo, a miniature mobile persocom, transitions ownership from Hiromu Shinbo to Hideki Motosuwa following Shinbo’s exit. Resembling a palm-sized laptop, she measures 16 centimeters tall, sporting magenta hair and eyes alongside a pink genie-inspired outfit. Engineered for charm and exuberance, she bursts with animated quirks—orchestrating morning exercises and dancing idly on standby.

Her story intensifies when Shinbo employs her to assess Chi, triggering a system failure that demands hardware overhauls: a main memory replacement in the anime and a supplementary video card upgrade in the manga. Post-repair, Hideki assumes ownership. She integrates into his routine, offering logistical aid and companionship, though her unpredictable antics prompt fellow persocom Kotoko to deem her logic incoherent.

Security distinctions emerge in her activation codes: the anime blends hiragana and katakana for "Chobittsu," while the manga opts for "Chobits." She proves pivotal during crises, partnering with Kotoko to document incriminating evidence against an adversary.

As a narrative fixture, her design and protocols mirror themes of persocom utility intertwined with approachable personalities. Limited expanded lore confines her to a steadfast dual role—whimsical humorist and pragmatic aide—without deviation into deeper backstory or evolution.