Who is this character in a green shirt swinging a flagpole? I found this image today, and am curious as to who the character therein is.



The only English result produced by a reverse image search is this blog post which suggests that the origin is the anime Durarara!!. However, I've been looking at various Durarara!! character profiles, such as the category on their Wikia and this image of all the major characters, and this boy does not appear to be in them.

All this leads me to believe this shot might be a flashback or something (as he looks quite a bit younger), or perhaps another anime if I've been misled...

What is the name of this character?
This is actually just HEIWAJIMA Shizuo when he was younger. There's a flashback in episode 7, lasting from roughly 06:48 to 11:12, that shows how Shizuo got to be so strong in the first place. Your screencap occurs around 07:55.