Before actor Masakazu Tamura（田村正和）became famous as Japan's version of Columbo, aka master detective Ninzaburo Furuhata（古畑任三郎）, he was quite the head-turner in a number of those late 1980s trendy dramas on TV, including one such rom-com called "Atsuku naru made Matte!"（熱くなるまで待って!...Wait Til It's Hot!）. From what I've read on J-Wiki, it sounds a bit like "The Odd Couple" as his character, a widower manga artist who's been isolated in his urban condo, is invited by his cousin who's recently separated to share a mansion in the ritzy Den'en-Chofu area of Tokyo.
My student used to live there and when I was teaching him in person a decade ago, he drove me from Den'en-Chofu Station to his place and vice versa. Yup, indeed, there were some nice palatial estates there although I'm sure that they still pale against the celeb homes of Beverly Hills.
Generally speaking, I don't know the gamut of theme songs for these trendy dramas and their characters of leisure. The one that I know off the top of my atama is Carlos Toshiki & Omega Tribe's "Aquamarine no Mama de ite" (アクアマリンのままでいて), the Resort Pop theme song for "Dakishimetai!"（抱きしめたい!...I Wanna Hold Your Hand） starring the Asanos, Yuko and Atsuko（浅野ゆう子・浅野温子）.
However for "Atsuku naru made Matte!", the theme song went more into a flirtatious and snazzy direction with "Joudan janai Asa" (No Joke Morning). Plus it was recorded by Miki Hirayama（平山みき）, who up until this point was only represented on "Kayo Kyoku Plus" by her trademark tune "Manatsu no Dekigoto" (真夏の出来事）from 1971. Underlaid with a contemporary rhythm track, "Joudan janai Asa" floats above with some old-time jazz arrangement provided by the brass and Hirayama's vocals. I think it's safe to say that the song fulfills both the romance and the comedy aspects for the show. Yasushi Akimoto（秋元康）provided the lyrics while Kyohei Tsutsumi（筒美京平）composed the song.