Kōya no Shōnen Isamu appears in the table of contents of 10 Weekly Shonen Jump issues (週刊少年ジャンプ, Shueisha), between 1971 and 1973. Its earliest recorded appearance is issue 39, 1971, published September 20, 1971. No final chapter is marked in the sources; the database records it up to issue 50, 1973, published November 26, 1973.