Look, I've read the definitions.

Shounen
A work intended and primarily written for males. These works usually involve fighting and/or violence.

Seinen
Manga and anime that specifically targets young adult males around the ages of 18 to 25 are seinen titles. The stories in seinen works appeal to university students and those in the working world. Typically the story lines deal with the issues of adulthood.

The definition for the shounen genre seem to describe Delusional Boy much more perfectly.
Anyone have a counter opinion on this?

With the amount of blood and violence this manga contains I think it qualifies for seinen. Just because it is a fighting manga doesnt make it shounen.
Examples:
Dorohedoro
Jackals
Dendrobates

Shounen is a demographic.

This manga should be labeled as shounen or seinen depending on the demographic it's being sold to. Since the info page doesn't list the magazine it's serialized in, there is no definite answer.

Didn't fully read the series yet, but from the description and art it defeinitely seems to be geared towards more mature readers.
The "Genres" on this site are pretty ...peculiar, but usually Shounen should be geared towards boys and male teens, while Seinen is more for young(-ish) men

[img]http://i59.tinypic.com/zxm8o8.jpg[/img]

as badkarma said

but this basically only applies to japanese manga, other series where it is not possible to discern this schouldn't be labeled at all, e.g. webtoons, but people always add something after some time...
I even remember double demographics there...

someone should lock the field until there is more information available

there haven't been any points made for either of the demographics, there are plenty seinen with fighting and plently shounen with blood and violence.

someone who read this and is familiar with both genres should comment or this will be just a useless superficial disussion...

in need of romance?
uncommon, sad, sweet