To continue:

since this thread hasn't really been giving me any answers,
I've tried to do some more research on the web. FPS games aren't popular
at all in Japan, for a few reasons. As stated earlier, its not the blood
and the guns that disinterest the Japanese gaming audience, rather
it must be some other factors unique to the FPS genre itself.

There has always been a rumor that the Japanese don't like FPS
games because it gives them motion-sickness. I doubt this is true.
But, I have seen some Japanese game directors comment about the FPS genre.
They have said that FPS games are "too open-ended", and that while western
gamers prefer to figure things out by themselves as they go along, Japanese gamers prefer
more tutorials. Additionally, a recent poll taken in Famitsu
asked gamers why they aren't interested in FPS games. The majority
of respondents said that, "They didn't know what to do". A second factor that I've seen mentioned is a matter of
immersion. In many FPS games, the character you play as is often one without a face
or personality, because its supposed to represent the gamer. Western gamers tend
to place themselves into the shoes of the main protagonist, whereas Japanese gamers
tend to root behind the main protagonist, which the FPS genre often lacks.
The third factor is one that applies to western games in general.
When making games, Japanese developers put more emphasis on graphics
and debugging, whereas western developers put more emphasis on quantity, content,
and creating new features. As a result, a lot of western games
have an "unpolished" look to them that drive away many Japanese consumers.
There are some things that western audiences are willing to tolerate and ignore,
such as clipping and glitches and limbs going through walls. However these kinds of things
aren't as acceptable in the Japanese gaming market.

So there.