I think the joke here is that, due to the japanese being so overworked, they barely have enough time to have relationships with members of the opposite sex, to the point where just spending time with someone who could show you basic affection and kindness is considered unheard of, let alone getting laid.

It's not even about sex now, it's about having someone you care about to spend time with.
this is why dating sims are so wildly popular in japan, it's gotten to the point where there's a literal market of games thriving because people need a woman to approve of them and talk to them, spend time with them and vice versa.

So the joke here is that a succubus can't get laid in japan because in exchange for their vitality, a japanese worker would just want to hang out, simply because they never have enough time to actually get a girlfriend.

This isn't even exclusive to dating sims either, lately japanese women have entered a new kind of business similar to prostitution, except instead of sex, they just hang out with the client, go on harmless playdates with them, like to arcades or just to their homes to talk about stuff.

I shit you not, women get paid more to hang out with men than to have sex with them in japan and it's a thriving business.

that's how starved for female affection these people are.

Jesus japan needs to stop working so hard, their society's gonna go the way of rome at this rate.