When I was looking for a video of Sentimental City Romance's (センチメンタル・シティ・ロマンス) "Natsu no Hi no Omoide" earlier today for the article, I also found another song with the same title.
This "Natsu no Hi no Omoide" (Memories of A Summer Day) was recorded by the beautiful Teruko Hino（日野てる子）back in January 1965. Unlike the happy-go-lucky namesake by Sentimental City Romance, the B-side to Hino's 7th single "One Rainy Night in Tokyo" (ワン・レイニー・ナイト・イン・トーキョー) is a much more bittersweet affair and another example of how Japanese songwriters loved to use the seasons as analogies for the status of the heart. Written and composed by Domei Suzuki（鈴木道明）, Hino sings about walking alone on that lonely beach during the height of winter while remembering the happier days at that same place when she was walking with that fellow who's no longer by her side.
Hino was born in July 1945 which means that she recorded "Natsu no Hi no Omoide" when she was still a few months under 20 years of age. That was quite the rich voice she had even back then. Its quality reminded me of another honey-coated set of vocals belonging to Naomi Chiaki (ちあきなおみ). That B-side became one of her trademark numbers which helped get it and "One Rainy Night in Tokyo" attain big hit status with over a million records sold. On J-Wiki, Hino has been categorized as a chanteuse of Hawaiian melodies but the original recording was definitely in the Mood Kayo area, although her above performance on stage was arranged with that Hawaiian feeling in mind.
The singer was born in Matsuyama City, Ehime Prefecture and debuted in 1964 with "Kaimana Hila"（カイマナ・ヒラ）, with at least 30 singles and 15 albums (including BEST compilations) under her belt up to the late 1970s. Hino appeared three times in a row on NHK's Kohaku Utagassen between 1965 and 1967 which included her rendition of "Natsu no Hi no Omoide".
Sadly, Hino passed away at the age of 63 in 2008 due to lung cancer.