Anime Crossover: My Online Romance is Megumi Kato

[Saekano: How to Raise a Boring Girlfriend + The Quintessential Quintuplets + Oregairu + Dress-Up Doll + A Silent Voice... tentatively]
Yuta Kijima unexpectedly transmigrates to an island nation. His previous life was unremarkable, but in this life, with a proficiency system, he is determined to live a more comfortable life.
Unexpectedly, not long after I transmigrated here, I started an online romance with a Japanese girl. I didn't intend to care about the vague online romance, but I didn't expect that my online love interest would be Kato Megumi, the understanding Kato Megumi, the tsundere Eriri with max tsundere attributes, and the black-stockinged senior Kasumi.
In the days that followed, various romantic opportunities kept appearing around him.
"I will always love Kato Megumi!" "Eriri is the best!"
(All characters in this book are adults; please refrain from negative comments if you disagree.)