warui series has 3 couples: [1-?], [2-?] & [3-?]
their stories have different numbers of volumes. the most volumes have first couple [1-1]- that's the first volume of the first couple, [1-2]-the second one... and so one
the series goes like this:
Vol 1 Warui Koto Shitai [1-1]
Vol 2 Waruiko Demo Ii? [1-2]
Vol 3 Kirai ja nai Kedo [2-1]
Vol 4 Koi Ja nai Kedo [2-2]
--- Warui Koto Bakkashite GomenNasai [1-3 &/ 2-3]
Vol 5 Warui Yatsu Demo Ii [1-4]
Vol 6 Mujihi na Otoko [3-1]
Vol 7 Warui Koibito ja Dame? [1-5]
Vol 8 Kare ja nai kedo [2-4]
Vol 9 Mujihi na Anata [3-2]
I Want To Be Naughty!