Aishiteruze Baby ★★, Vol. 6

Yuzuyu has a new classmate, Aya, whose older sister takes care of her just like Kippei takes care of Yuzuyu. Unfortunately, Aya and Yuzu overhear Aya's sister complain to Kippei about having to take care of a small child. Kippei starts spending time with Aya and her sister to help out, but Kippei's girlfriend Kokoro is the one who needs Kippei the most... -- VIZ Media