I didn't say Spanish is ridiculous either, I said maybe you thought 'Japanese speaking Spanish is ridiculous'. But really the whole post was tongue-in-cheek, and I guess you didn't pick up on my Dragon Ball Z punchline.

As for 'why are they spanish names', the creator probably wanted to do something different and thought it was cool. Possibly the same reason he named the manga 'Bleach'. The same way you might see people with T-shirts or tattoos or something with Japanese/Chinese symbols, Japanese people walk around with random English or other languages on their clothes.

It's exotic.