Premieres January 12, 2025. Check out the ANN article for additional information. Synopsis for the first season from AniList:
Rentarou Aijou was rejected 100 times in middle school. He visits a shrine and prays for better luck in high school. The God of Love appears and promises that he’ll soon meet 100 people he’s destined to date. But there’s a catch—once destiny introduces someone to him, the two must happily love each other. If they don’t, they’ll die. What will befall Rentarou and his 100 girlfriends in high school?
The biggest age gap is between the MC, aged 16 and his 89 year old girlfriend, who is the grandmother of his other girlfriend. As you can see, this series takes itself very seriously.