Banana Fish

Nature made Ash Lynx beautiful; nurture made him a cold ruthless killer. A runaway brought up as the adopted heir and sex toy of "Papa" Dino Golzine, Ash, now at the rebellious age of seventeen, forsakes the kingdom held out by the devil who raised him. But the hideous secret that drove Ash's older brother mad in Vietnam has suddenly fallen into Papa's insatiably ambitious hands—and it's exactly the wrong time for Eiji Okamura, a pure-hearted young photographer from Japan, to make Ash Lynx's acquaintance…

The five oneshots at the end are Banana Fish another story (Mangaupdates link).

A collection of Banana Fish side-stories that take place before and after the main story. Contains spoilers for the ending of Banana Fish itself.

1. ANGEL EYES
2. Hikari no Niwa - THE GARDEN WITH HOLY LIGHT
3. PRIVATE OPINION
4. Ura BANANA
5. Fly boy, in the sky