When they get really upset or serious about something, they get all powerful and start acting like a different person, or get overcome by some inner demon/monster or kinda in a trance. A berserker?

Ones I've already read/reading are...

Naruto (fav characters: Gaara and Naruto. Inner demons RULE)
666 Satan (fav characters: Jio. He gets all cool especially after the 2nd time skip)
Kyou Kara Maou (fav: Yuri of course cause he's awesome when he goes maou.)
Nabari No Ou (fav: Miharu cause he's got a super strong inner power. Yoite is cool
too cause the Kira can kill anyone)
Ichi the Killer (fav.: Ichi! Hahah he's crazy)

male leads please. Thanks. Unique character designs are a plus.

Ai Kora

its a comedy where the main character gets crazy strong when his.....well, read it and see.

Definitely, Nurarihyon no Mago. Kateikyoushi Hitman Reborn! would probably fit as well.

[img]http://i56.tinypic.com/acfmfo.png[/img]

Thanks for the recommendations, I will check all of them out!

Berserk. XD Getting possed and crap with his inner demon thingy doesn't really happen until the more recent volumes, but its really what you want.

Does the walker choose the path, or the path the walker?

Berserk looks sweet. I will definitely read that after I get my work done.

Dragon Ball definitely. 😃

Kurogane No LineBarrel
inuyasha

[img]http://www.squiby.net/view/4914221.png[/img] [img]http://www.squiby.net/view/4914230.png[/img]

How about some manhwa, these are some of my recommendation, check it out:

ID - Really awesome man, you should really check it out
Chronicles of the Cursed Sword
King of Hell

I second Nurarihyon no Mago and you might wanna check out Kekkaishi(it is a bit slow but later on it'll get interesting, there're like 15+ volumes for you to chowed 😁 ) also. 😎

You like the things that i HATE, and i HATE the things that you like

altho i agree that ID is "awesome", but there's no really "overcomming" characteristics in that manwha... There is the "hidden power" criteria, but he has full control over it. 😲 Just saying... not exactly what you're looking for but it really is a great read. It's quite unique~ (none of the typical shounen cliche characteristics found there)

The Company
[b]Batoto

One Piece

Quote from Grumpy

altho i agree that ID is "awesome", but there's no really "overcomming" characteristics in that manwha... There is the "hidden power" criteria, but he has full control over it. 😲 Just saying... not exactly what you're looking for but it really is a great read. It's quite unique~ (none of the typical shounen cliche characteristics found there)

That's... not exactly true. There are times when id overuses his power, and begins to change into someone else. But I'll admit that it doesn't happen very often.

This signature was recovered from Hades to serve in my rotting armies.

History strongest disciples keneichi

Rurouni Kenshin - Kenshin is an extremely skilled swordsmen normally, but he's still a pacifist. But if you get him angry, well, you really do not want to get him angry.

Black Cat - The main character is very similar to the above, but the story is very different.

Tsukihime - Pretty much everyone has a super powered evil side including the main character and the usually ditzy female lead who when angry says things like "Destroy. Destroy. Destroy. Slowly, completely, gently beyond comparison, cruelly to the point of numbness, I'll violate your life. That's right. The instant I tear off your limbs, rip open your chest and pull out your intestines, biting into your neck as you ask for mercy, chewing through your eyes and spreading your brains on the ground like butter...!" and she means every word of that.

Watashi no Messiah-sama - the main character also counts.