One of the longer titles of a J-Pop/kayo kyoku song I've ever come across, "Heart & Hard: Toki ni wa Tsuyoku, Toki ni wa Yasashiku" (Strong At Times, Kind At Times) has become one of my favourite Mariko Takahashi （高橋真梨子）ballads over the years. I first heard it on a BEST compilation CD of her works that I bought years ago, and although it didn't grab me initially, it was able to grow on me rather nicely.
It's another wonderful Takahashi-and-Ami Ozaki collaboration just like the former's first solo single, "Anata no Sora wo Tobitai"（あなたの空を翔びたい）from 1978. The version at the link above is actually from her "Special Best -- Sing" album of 1995; there is a bit more of an urban kick to that version but I prefer her original from June 1979 which came out as her 3rd single. That original version has a softer edge with a lilting piano and strings that belie Takahashi's pop/folk roots from her time with Pedro & Capricious, but also contains a fine electric guitar bridge...it is that instrumental combination with her voice that made me fall in love with her material in the first place. There is also a bit that reminds me of Yumi Arai's （荒井由美）"Sotsugyo Shashin"（卒業写真） in the refrain.
"Heart & Hard" was also included on her 2nd album, "Sunny Afternoon" which was released in February 1980.
Ami Ozaki（尾崎亜美）, the writer and composer for the song, has done a lot of covers of her contributions to other singers over the years but I'm not certain whether her version of "Heart & Hard" ever came out even as a track on one of her albums. However, here she is above with her cover of the ballad in concert.
Purely by accident, I discovered a jazz version of "Heart & Hard" by composer-arranger Junichi Kamiyama（神山純一） that sounded pretty good so I have put it up as well. It's a track on one of Kamiyama's series of tribute albums "JAZZ de Kiku" covering various artists such as Takahashi. The full title is "JAZZ de Kiku: Takahashi Mariko Sakuhinshu -- Hagayui Kuchibiru"（JAZZで聴く～高橋真梨子作品集～はがゆい唇....Listening Through Jazz: The Mariko Takahashi Collection -- Impatient Lips）.