takahiro harada's art? since he's like the main artist for all disgaea games

Well yeah, was simply too lazy/forgot to tag it.

Hmm, is something lost in translation or is vomiting blood really seen as a sign of happiness in Japan ?

It's really a metaphor.

Well yes, I assumed there wouldn't be any actual blood vomiting involved, it just struck me as very odd that someone would say "I'm so happy, I'm about to vomit blood!" so I assumed either I or the translation was missing something, and asked to see if the more knowledgeable people here could say which. :)