You mother had a one night stand with either Daki Takahashi or Kai Yamaguchi and got pregnant and out of spite and financial trouble she drops you off in front of an apartment knocking on it and walking away

The door opened as Daki yawned standing in the door away with bed head and in his boxers, trying to find the source of the knocking, his groggy expression showing how tired he was. He ran a hand through his messy hair, sighing in frustration as he couldn't find anything.

"Who the hell is knocking?" he muttered to himself, rubbing his eyes to try and clear his vision. "It's too early for this shit..."