It's not a manhwa. It's continue from katsura hoshino if I'm correct.
*SPOILER ALERT*
It's about a boy who always plays the hero. One day he gets involved with a monster while trying to save his best friend. He ends up dead but is revived thanks to an odd being. Now a zombie, the boy helps the odd being with fighting against the millenium earl (the bad guy). But in this war against the millenium earl it is dangerous to have close relationships with anyone so the boy cuts all ties with everyone and goes on a journey. (But really the boy isn't sad about it at all)Added (2016-07-30, 7:08 PM)
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Wait. Ignore my previous message.