Believe ~Shitsuyoku no Tenshi-tachi~

Main character is an excellent student trusted all over the school. However, one day he gets to die. A mysterious man appears before him and says that protagonist's soul can be pardoned in exchange for 200 million yen. The end date is his next birthday. But how is protagonist supposed to gather such an outrageous sum of money with just working part-time at a coffee shop? He finds a way out. He starts to lure his friends at coffee shop basement and there train girls into slaves.

[From vndbreview]