Beast Master (manga)

Yuiko Kubozuka is a high school student who loves animals with a burning passion, though animals unfortunately hate her and flee from her whenever possible (usually causing damage to her in the process), prompting her friends to say that she should focus that energy on a boyfriend. She, of course, isn't all that interested, until one day, while attempting to retrieve her (unwilling) cat from the local park, a mysterious boy with a wild look in his eyes brings it back down with little trouble. She thinks little of it until the next day, when the boy transfers into her class. His name is Leo Aoi, and, despite his fierce expression, he's really a sweet, naive, gentle hearted teen - at least, until he sees blood. When Leo sees blood... Well, let's just say that he isn't exactly human when he sees blood...

Because Yuiko is the first to see beyond his frightening expression, Leo quickly becomes strongly attached to Yuiko, who is his first friend. Yuiko is unique in her ability to calm Leo down when he goes into one of his rages, and slowly, they begin to fall in love. However, soon, Leo's past starts to catch up with him, and it threatens to rip the couple from each other's arms.

Beast Master is a 2006-2007 shojo manga, written by Kyousuke Motomi.

Not to be confused with the 1995 manga of the sane name by "Euclid".

Tropes used in Beast Master (manga) include:

Adorkable: Leo, Leo, Good God Leo!
Adult Fear: Attempted rape on Yuiko. The rapist pretends to feel ill, and Yuiko helps him. Once she gets him near a bench, though...
Berserk Button: Literally when Leo sees blood.
Cooldown Hug: Yuiko to Leo. She's the only one who can do it, too.
Cute Little Fangs: Who else but Leo?
Disappeared Dad: Nobody knows where Leo's father is. He shows up in the second volume for some plot movement.
Don't Try This At Home: When Leo climbs a telephone pole to get a scent on a missing dog, Yuiko briefly breaks the fourth wall, saying to the readers, "Don't try this at home."
Face of a Thug: Leo. With the sweetest possible personality behind it, of course. Also, Boss and his group.
Friend to All Living Things: Leo. Yuiko tries to be, but, well, she's a little too enthusiastic...
Good Scars, Evil Scars: Leo has several scars on his shoulder, chest, stomach and back but they do not in any way detract from his appearance.
Hands-On Approach: Leo gets behind Yuiko and calms her down so some birds will land on her.
Hidden Depths: Boss, who appears to be a stereotypical yankee at first glance, but is actually a very kind guy who cares a lot about his friends, patrols the neighborhood when there's an attacker on the loose, and takes care of an abandoned German Shepard. Word of God says that his biggest crime is not adhering to school uniform regulations.
Noble Savage: Essentially how Yuiko imagines Leo was during his time "living in the wild". It's noted that it was probably completely different, though.
Raised by Wolves: Leo, of course.
Savvy Guy, Energetic Girl: Inverted, except around animals.
Woobie: Leo. He just wants friends, but he's got such a scary face...
Yandere: Sasamoto's girlfriend.