Leo has 'black eyes' which means they have a rim around them so it looks like he has bags or eye-liner on but in this case it makes Leo look like a wild animal instead of the kind-natured boy he is.
The first friend he made at his new school was Yuiko Kubozua who, the her classmates claim, has 'tamed the beast' and is the beast master. Leo was on the roof of the school when he and Yuiko met properly. The day before he had saved Yuiko's cat. Yuiko was going to offer Leo some tea when a flock of birds landed on Leo. Since Yuiko is crazy about animals, she completely forgot about the tea and dropped it on the floor.
Leo, hearing the noise, turned around and picked up the tea. Handing it back to Yuiko, she told him that it was a gift for saving her cat. Leo was surprised and leaned forwads and asking, "I'm not scary?". Yuiko answered that he wasn't, which caused Leo to start crying with happiness since no-one had ever told him that before. For the first time, Yuiko saw the sweet hearted boy Leo was.