I think it was the Kazuhito Tadano affair in 2004 that first introduced me to Japanese gay porn. I became a fan and have followed it among others ever since. Yuki Sorci is a current favorite, though I don't think he's still active and I'm not sure how recent some of his vids are. I think my favorite of the Japanese production companies currently would be hunk-ch@nnel.
I don't mind the masking to be honest. It's like condoms. Wear them, don't wear them - I don't care. At some point I stopped noticing. IMO one of the most common pitfalls in gay porn is too much camera time spent on the genitals. I mean I get that it's porn, but for me it's as much about the facial expressions, the attitude projected by the performers, and beautiful bodies, that make a scene successful. Genital closeups should be frequent enough and from varied angles in each position assumed by the performers to establish what's happening, give us a good closeup look at the parts and keep it interesting. Beyond that, I'd rather see wider shots and focus on other things.
I believe they pixilate the penis and scrotum, not the anus - unless a penis is stuck in it. They probably pixilate the vaginas in straight porn, I don't know.
They have their special areas of interest that stand out. One sees lots of lube being used all over the body and often applied and massaged through the underwear before it's removed. You don't see as much of this in other porn. They also seem to especially enjoy egg-like battery operated toys that vibrate and can be inserted into the anus as well as dildo-like probes and plugs that bend and twist.
The usual themes seen in other porn are present - the twink, the student, the athlete, the salaryman, and less usual - the sumo wrestler, the samurai. There's a wide variety of looks, body types. ages, fetishes, etc.