Hideki discovers that his feelings intensify for Chi whether she is a persocom or not, despite other horrible experiences involving persocoms that happened to his friends. Chi becomes aware of her purpose through a picture book series called A City with No People which she finds in a bookstore.
The books speak about many different things involving human and persocom relationships: persocoms and their convenience towards people as friends and lovers, how there are things that they cannot do and questioning whether a relationship between a persocom and a human is …

The series deals with issues and ideals of virginity, and sexual intercourse in that Chi is effectively incapable of sexual intercourse (in the manga and in the series), as attempting to do so would “reset” her, so she must therefore only entrust her body to someone who cares for her well-being as opposed to a purely sexual relationship.
Freya explicitly tells this to Hideki in the final scene of the manga, that to have Chi, pointing between her legs, means that Chi would lose all her memories. However, earlier in the …

As the series progresses, Chi begins to have visions of another persocom who is identical to herself, and eventually learns this is Freya, her twin, and that Chi was originally called Elda; after Freya fell in love with her father and creator and had her heart broken (she couldn’t muster the courage to admit her feelings in the anime), her memories were downloaded into Chi, before her system was wiped at her own request.