You act like this isn't common as heck in manga regardless of gender? Do you know the shear quantity of highschooler x teacher shiz, or office worker x highschooler stuff there are on this site? Also, there's tons of stuff about small children and adults on this site. Have you never read manga or watched anime?
I like the story. their persona are flipped around between their real life and their vtuber self. the one who is actually an OL become the younger one as a vtuber, while the one who actually high school girl become an adult woman as a vtuber. this isn't the first time I read the large age gap romance shoujo-ai, but their vtuber self become unique gimmick, which I like it I hope they doing more than just collaborations in the future story