Yes, I've played "Nicole" Otome game and I really liked it ;DD I've got Kurt's Best ending at the first time, But I played some more to make a Walkthrough for you, girls ;DD
Requirements:
To get normal ending, have 900+ on stat that the character likes the most,
also your relationship should be 100.
To get special ending, have 900+ on stat that the character likes the most, have your relationship on 100, and solve the mystery (Clues should be maxed, and you have to see all of the mystery events).
The raise in Clues depends on your other stat (the stat related to the boy you're chasing, of course). The higher the other stat is, the