CCC Route

Buy Uniform for Sakura (expensive key item in 1st chapter , talk to her after buying it)
Go to the medbay before entering Rani's dungeon
Ask BB why she calls you Sampai in BB Channel when the chance appears (on rani dungeon 2nd floor , the option has an special simbol on it)
Talk to Sakura before fighting Rani
Talk to Sakura before entering Lips's dungeon
Choose the options : 「それは出来ない」「トドメを刺さない」 after defeating lips
A different event will occur after getting Jinako's first SG
Talk to Sakura before entering Jinako dungeon floor 2
Go to the medbay and give money before entering Elizebeth Dungeon floor 2
Head to the council room immediately after entering Melty's dungeon
Head to the medbay, give Sakura cash and choose :桜を労る
Talk to Rani before heading to Melty dungeon 3rd floor, then head to medbay and choose: 「…それは出来ない」
After getting the SG on Melty floor 3, BB will appear and choose: BBを心配する
Different event before entering Melty
After defeating Melty, choose: 「…それは、出来ない」「…このまま、止めさせない」
Talk to Sakura in medbay
Auto event, choose: 「自分たちと桜のため」
Entering Sakura, choose 「桜のために」
In chapter 7, head to the medbay after getting the new costume and you will get BB's 3rd SG