Pita-Ten Vol 1

From the Tokyopop edition

Pitaten is the irresistibly delightful story of Kotarou Higuchi, an elementary school student whose mother died and whose father is often away on business. He is doing his best (and failing) to pass the entrance exams for middle school; and his life is made even harder when his new neighbor Misha just won't leave him alone. She claims that she is an angel and that she will do her best to protect him... Misha has just moved in next door to Kotarou Higuchi and swears she will protect him at all costs. Unfortunately, she's not too familiar with the ordinary world, as she is an angel who has lived in Heaven until recently. She has no idea how things work on earth and ends up causing more trouble.

Source: Anime News Network Encyclopedia