I've got a couple non-manga recommendations:iZombieMy Life as a White Trash Zombie 3n2q1v

3x3 eyes, it's pretty much about that.

Wake Up Dean

Raiders is what you want, im not sure if its online though cos its licensed. Its got a male zombie protagonist and the sustenance side and he's tortured. They arent mindless zombies, just immortal and some need to eat flesh to not rot. Also cradle of monsters has various characters turning or getting bitten

including two who could be seen to be the main characters but theres various groups and its mostly a zombie survival....on a cruise ship XD

The only undead manga I have found that somewhat fit your request are: "Tokyo Ghoul" and "Variante" The second is a bit of a mind rape though. Both have characters terrified of becoming the monsters they are told they are.