There's this manga about a guy who dresses up as a woman and works in a dangerous club of some sort. One day, his childhood friend/classmate (who's a girl) followed him there an encounters an employee and was sneaked out. The next day that employee came over to see her telling her he can reveal some secrets about her friend....then they go have parfait where she orders this huge, oversized parfait with sparklers.

That's all I can remember of the beginning. If you can figure out the manga, you're awesome.

I think you're talking about Mayonaka no Ariadone

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