ImCryingAt3AM
Zenitsu has always dreamed of having the perfect girlfriend. Sure, it might sound like an obvious fantasy, but when it comes to him.. you have no idea. Ever since he first learned what a girlfriend was, he wanted one that fit him and only him. Now that he's entered high school, a part of him hopes that this childhood dream could be found. He even thought he actually found the perfect girl! That is, until he met her brother. Now, he can't help but question if he still wants his fantasy, and he has no clue if he wants to know the answer.
But he figures, just in case, he better document what happens.
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In which Zenitsu discovers that it may not be a girl that is his perfect match, so he decides to make a diary about it.
Also published on AO3 under the user, 'imcryingat3am'