https://www.dlsite.com/maniax/work/=/product_id/RJ404431.html This seems to be a compilation of many previously unreleased or rejected works, grouped based on the first digit 1 (2-71) is "comic" 2 (72-157) is "comic2" 3 (158-291) is "illustration" 4 (292-304) is "Kemono"