Here is the full list of all 13 HENTAI REDEMPTION achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Kill 100 enemies.
Kill 90 enemies.
Kill 80 enemies.
Kill 70 enemies.
Kill 60 enemies.
Kill 50 enemies.
Kill 40 enemies.
Kill 30 enemies.
Kill 20 enemies.
Kill 10 enemies.