The childhood friend of Tomoki Sakurai, Sohara Mitsuki is the one who takes him to meet with Eishiro Sugata about his recurring dream. She severely punishes Tomoki whenever he acts perverted around her with a "killer" karate chop that leaves him near death. She lives across the street from him.
The childhood friend of Sora no Otoshimono's male protagonist Tomoki Sakurai, Sohara Mitsuki lives across the street from his house of the outskirts of the town of Sorami, Japan. She has been friends with Tomoki since her childhood, when her weak immune system and constant battles with illness did not allow for her to attend school or make any other friends. She tries her best to keep Tomoki in check (like correcting his perverted behavior with a brutal karate chop that knock him senseless) and tries to be involved in his life as much as he was involved with her when she was sick and he was her one true friend. She has very strong feelings for Tomoki (which she denies and hides from others), and she becomes quite jealous when not only Angeloid Ikaros moved in with him, but Nymph and Astraea as well (she sees Tomoki falling for one of the Angeloids instead of her).
Sohara Mitsuki was created by Suu Minazuki for use in the Sora no Otoshimono manga. It is not known exactly as to what inspired her creation at this time. Sohara first appears in Heaven's Lost Property #1 and Sora no Otoshimono: Volume One.
Sohara does not feature any special powers or abilities (like the ones seen in the Angeloids), but she is best known for having a brutal, punishing Karate Chop attack that she uses to crush the hapless Tomoki with whenever she believes that he is acting too perverted around her.
Heaven's Lost Property the Movie: The Angeloid of Clockwork
The first movie in the Heaven's Lost Property series, The Angeloid of Clockwork supposedly focuses on the Hiyori Arc from the Sora no Otoshimono manga.