Chikyu Misaki

Chikyu Misaki (地球美紗樹, Chikyū Misaki) is a 3 volume manga series by Yūji Iwahara.

Plot
The series follows Misaki, a 14-year-old schoolgirl that comes to the town of Hohopo to inherit her grandfather's house and land. Once there she soon discovers that the lake contains a "hohopo", a creature similar to the Loch Ness Monster in appearance that has the capability to transform into a young boy. Naming him Neo, Misaki soon has to keep him safe from people that would harm him or exploit him in order to gain fortune and fame. During her misadventures Misaki gets kidnapped by a woman intent on retrieving gold that sunk to the bottom of the lake after a botched kidnapping, but is eventually set free. Hiding Neo becomes more of a challenge after he becomes incapable of transforming back to his human state. As a result a hitman that came to the town looking for the ransom money starts hunting for Neo in order to sell him as a strange find. During all of this Misaki begins to remember things about her past and realizes that she has a strong bond to Neo due to a set of experiments that her grandfather performed on both her and Neo.