30 Kin Sore wa 30-sai Miman Okotowari no Koi (Season 1)

At 30 years old, Moriyama Shino has a fulfilling job but no love life. She wants to date and get married to someone the same age as her. However, one day, she gets confessed to by Sato Mayuki, a man 9 years younger than her. Surprised but impressed by his straightforward confession, she agrees to date him until she finds a marriage partner.