That's a good question, Japanese-wise
First, I just searched for "Group Bukkake JAV", and it exists as a
genre on MissAV, though I'm not sure if it's any good in terms of precision. So then, I looked through the titles there and found a few that had lots of men in a bukkake session to see what words are being used in Japanese on the DVD cover, and the most "effective" in terms of search seems to be 輪姦 ("gang r***"). I decided to search for that to check (searching for 輪姦ぶっかけ, i.e. "gangbang bukkake"), and the results seem to be fitting
So fitting actually, that there was this cover that immediately caught my eye, and it's
a whole series that I have never seen before. Knowledge (in our case, language knowledge, and even more precisely, Japanese knowledge) is power
GVH-282
Then I also remembered about
a recent post in one of the gokkun threads here, and checked the texts on the cover as well, and here we encounter a big problem for JAV search: the series name is often not really descriptive and can be applied to almost any porn (I mean, "Dream Woman" could be a softcore porn title as well, or just an erotic novel title, or romantic, or...)
Anyway, I decided to check if Japanese AV sites have something more than this vague title listed for this series, and (again, searching in Japanese, which is almost always better in case of JAV) I found
the page for the series on the maker's official site
There,
volume 80 caught my eye because of booba, and yeah, this whole series seems to be what you're looking for. 90 titles, man, brace yourself. And as for the key words, and I would highlight 発 (shot), 連発 (consecutive shot), 集団 (group, crowd). And if you look more at the titles you already know are group bukkake, you can find even more fitting key words
