Haré+Guu

Haré+Guu (ジャングルはいつもハレのちグゥ, Janguru wa Itsumo Hare nochi Gū) is a Japanese manga series by Renjuro Kindaichi which serialized in Monthly Shōnen Gangan. An anime adaptation for 26 episodes were made, followed by two OVA sequels: Haré+Guu DELUXE and Haré+Guu FINAL.

Plot
Haré is a 10-year-old boy who lives with his mother Weda in a small village in a very strange jungle. Haré's mom is a bit of a "party girl" who likes to sleep all day and party all night. Things change one evening when Weda comes home with a little "playmate" for Haré, a pretty little girl named Guu. But when Haré wakes up the next morning, Guu has "transformed" into a sullen, nasty and sarcastic joker who takes great pleasure in making Haré's life utterly miserable. Guu can also swallow anything, and regurgitate it whole. Guu also seems to have various magic powers, which lead Haré to consider her a demon of some sort, but he can't convince most other people of that.