Here is the full list of all 31 Guilty Summer Kiss 2 - there are Bloody Secret achievements.
See the fight of Nakahara sisters
Betray Arisu
Show Lisa the photo of Arisu
Become responsible for Miya's reclamation
Say "No" to Rei
Find a new body for Hisano
Prefer Miya to Lisa
Let Rei live in your house
Be saved by Miko
Not to step on the shoelace when running away from Miya
Get into someone else's body
Be killed by Rei
See Lisa betraing her mother
Talk to Miko all night long
Listen to Lisa singing
Kiss Lisa
Find Arisu
Agree to help Hisano for money
Tell Miya you love her
Be called boring
Die for Rei's sake
Be seduced by the headmistress
Not to go with Miya to the lab
Prefer Lisa to Miya
Find out what heterochromy is
Hug Lisa
To mix up Lisa and Miya
Have a successful date with Lisa
Put 100 likes to Hisano in underwear
Put 100 likes to Miya in underwear
Put 100 likes to Lisa in underwear