Matsunaga, a salaryman in his twilight years who spends his days going back and forth between Earth and other worlds, and Sena Isezaki, a neighborhood high school girl and former great saint, who secretly has feelings for him. After defeating an earth dragon with his enormous magical power, Matsunaga goes to Carnelia, the capital of Count Karius, and uses the materials to conduct business negotiations...? While enjoying such a fancy otherworldly life, Matsunaga returns to the earth and is contacted by Aihara, a former junior colleague at the company he quit. What was the message? I want you to go out with us. Well, on the premise of marriage. Her bombshell statement leads to a strange incident involving Seina...? And of course, in another world... "Sis, I've missed you so much! She meets Leviria, the daughter of Count Carius, who is also Seina's sister, and goes on a "sightseeing tour of Japan" with her. Can Matsunaga solve the events on earth as well as in other worlds? T
1 Chapter (Ongoing)

This has kinda a funny concept. Girl was an isekai'd saint (Truck-kun) from ages 6-11, and was assassinated, whereupon she returned to Earth. The MC gets stabbed protecting her from a stalker, and while she's in contact with him heals his stab wound (reawakening her magic, and his as well), and they get sucked back into Isekai land.
Complicated start, and I'm sure it'll be done for a reason (maybe so she can be his 'tour guide' in the other world? not sure).
But what makes it hilarious is that she's got a GIANT crush on him, and has for quite a while. No info on why so far (only 3 ch TL'd), but she's now 16 and he's, what, late 20s? It's just hilarious how much she crushes on him and is incredibly proactive in pushing their relationship forward. She IMMEDIATELY decides to use a cover story of him being her husband.... why do they need a cover story? No clue, that's not important! lol.
We'll see how it goes, but it's certainly an amusing first 3 chapters.
(and no, the age gap doesn't bother me. She's VERY mature for her age - she's literally been through war and death and HAS BEEN STABBED TO DEATH, so no surprise she like older mature guys. He's very much NOT the one pushing for it either lol, it's all her.)