Primary Mini-Band [JAP] – 10. ぽつんと落ちてしまった.
Lp: きままなひび 〜夏から秋へ〜 (Kimama na Hibi), 1974.
Another reissue by Branco Label on 2016. You can buy the CD on the following links, i guess.
https://diskunion.net/jp/ct/detail/1006972743
https://page.auctions.yahoo.co.jp/jp/auction/c611311949