I was watching "Kayo Concert"（歌謡コンサート）last night. The theme was heartbreak ballads and they didn't fail to deliver with one of the big examples being "Ima wa Shiawase kai" (Are You Happy?). The original artist was Mitsuo Sagawa（佐川満男）who is not only a singer but also a tarento and actor. In fact, I think his acting resume is probably a whole lot longer than his music output.
However, "Ima wa Shiawase kai" is one of his biggies from 1968. Written and composed by Taiji Nakamura（中村泰士）, who would later compose the sad but proud "Kassai"（喝采）for Naomi Chiaki（ちあきなおみ）, Sagawa forlornly asks that title question to the girl he let get away from him. Unlike his bearded (!) appearance on that bright stage there, I think he ought to be strumming that guitar somewhere on a lonely street in the dark while wearing a trench coat. It may not have that Latin feeling that often comes through a Mood Kayo, but it's definitely a cry-in-your-sake ballad.
Although I don't have any information on its success in terms of rankings, it apparently was a huge hit according to J-Wiki, and Sagawa ended up on the Kohaku Utagassen for that song and has appeared a total of 4 times. One other piece of trivia is that he married singer Yukari Ito（伊東ゆかり）in 1971 but they divorced 5 years later.