Guardian Hearts (がぁーでぃあんHearts) is a Japanese manga series written and illustrated by Sae Amatsu, published from 2001 to 2005 in Monthly Shōnen Ace.

The first girl being the Guardian Heart, Hina, and to keep her identity secret he has no choice but to let her live with him.

To make matters more interesting, every girl whose secret or identity he discovers also comes to live with him and Hina.

She is a Guardian Heart, a protector of the peace and well-being of an assigned planet, who must always keep her identity a secret.

Hina is sent to Earth as a last chance to redeem her previous failures at keeping her identity a secret (said to be equal to a record).

This fails spectacularly as Kazuya witnesses her arrival (thus setting a new record for the fastest that a Guardian Heart's identity has been found out).

Initially she hates Kazuya, especially since according to her clan's traditions she has no choice but to become his wife (because not only has he seen her naked twice, he has also kissed her twice).

She fell in love with Kazuya at first glance, since she immediately confessed her identity to him on their meeting for the first time, but their conversation was interrupted by Guardian Heart.

Voiced by: Mayumi Shintani A female talking cat who started living at Kazuya's house but is closer to his mother than him.

When her ear is pulled three times she turns into a big monster which just looks like a Godzilla-sized white cat.