Involuntary Celibacy / Incel - The Culprit

It's more complex than that.

Japan has a big problem (well, several, but one of them is) "herbivore men", young men (not women) that are not interested in getting a GF or be in a couple

Their reasons are that it's hard, complicated, takes a lot of time and money and ultimately, isn't worth it, and they prefer using these resources on their career or leisure.

Now, don't get me wrong, if a cute girl jumps on you and asks to be your waifu forever with no catch, anime style, most would love that, which is why it's such a common trope. But that shit just doesn't happen, and Japanese culture, while more open that the west when it comes to sex, is also a fucking deathmaze when it comes to relationships in general. Work is hard, school is hard, time is lacking, and Japanese girls tend to be much more materialistic that western women. I've seen a few say openly that having a nice car/house is a requirement for someone to date them for example. Quite a lot of young people are NEETs, so they don't have that.

Not to mention, "courting" there (social cues, strict hierarchy, no touching, etc…) traditionally takes a lot more step than anywhere else.

So, to summarize, except in extremely rare cases, no hot girl will approach them because they aren't expected to make the first step, and they were raised with the idea that being in couple is a lot of work for not a lot of good things (the state of marriage there isn't pretty either.)

Actually the reasons are pretty well-documented please don't put me in your r/whoosh compilation