Plot.
No, really. Japan can make their plots tropey as hell, impossibly convoluted, and with a bunch of characters you'd punch in the face all day long. Yet their stories tend to be more memorable than the typical western stuff.
And when Japan goes stupid, they
really go stupid, which is absolutely a plus in my book. Yeah, I won't show some Japanese video game stuff to people coming to my house. I remember playing the FFX-2 massage scene with my mother in the house... luckily she didn't hear the moans before I could turn the volume down, LOL.
Japan isn't afraid to make things very, very weird. Western devs are scared to death to step outside invisible boundaries. Japanese devs smash those boundaries with a sledgehammer. They just don't care. I love them for that.
Gameplay. Japanese games usually don't try to put everything and the kitchen sink in their games, mapping 5 actions to the same button. Japanese gameplay tends to be straightforward. It can also be very repetitive, but that's a problem most games have anyway.
Cuteness. No one makes cute like Japan.
Creepiness. So many things and characters in Japanese stories and games are more or less intentionally ambiguous or creepy. Fridge horror is a strong feature of Japanese media.
Music. Japan still makes "gamey" music. The west has mostly abandoned that in AAA productions, and even indies (see: Hollow Knight) go for sombre ambient soundtracks. Hard to find "gamey" soundtracks in western games outside of indie retraux productions (see: Shovel Knight).
Japanese games can have stellar sound design that goes way beyond bombastic orchestral tunes and 7.1 surround. The sound design in games like Silent Hill and Breath of the Wild is phenomenal. It's not about making memorable music, it's about telling things and creating experiences with music.
Boobs. Sexualization, basically. Japan can get
extremely ridiculous on that front, mind. Stupidly big boobs, boob windows on everything, skimpy armor suits (I'll never forget the armor set you can buy for Jessica in Dragon Quest 8 right before entering the snowy area, LOL). There's a lot of bad-taste designs. Still, the good thing about Japan is that they prioritize a striking character design before other considerations, so they can produce characters that you'll never, ever, ever see in western games. Stuff like the notorious
Dragon Crown Witch and Valkyrie design is kinda gross, but it's tremendously funny, and it's still better than a lot of equally stupid Rule 34 fanart.
Excessive body and costume design can be funny as hell. I remember my mother and my aunt giggling maniacally while watching me and my cousin play Soul Calibur IV. "Look at those tits!" they went, and they were never worried we'd fap to Ivy (though I'll admit to fapping to Sophitia and Seung Mina back in the PSOne days
).
Women. Seriously. The best thing about the Japanese is that they can design stupidly busty characters like Senran Kagura's girls and
still make them more interesting women than you'll find in the majority of hyper-realistic western games. Women in Japanese games can be sexy
and cool. They can be complex, relatable and believable, something that so many western devs still struggle to come up with in spite of all their tech and all their female quotas in dev teams. There can be a lot behind the body of a female Japanese video game character, even if at the end of the day, you may still want to bang her.