if you want to do like MC in real life : DONT
whatever circumstance she have in her house/life, literally not worth anything in your life ruined
worst case, your life will be over when police / neighbor knew.
bad case, you need to take a responsibility and bye2 freedom
What's the point of the added detail with the little sister in the beginning?
Is it just to distinguish itself from all the other carbon-copy stories where the "real" little sister shows up in chapter 5 or so to live with MC for the first time? Here at least we know off the bat it'll happen.
Police in Japan can be so annoying at times. I seen a video of a Japanese police question a tourist, check her bags even though she carry nothing inside but make up. Like I get it they want to keep the peace but sometimes they went over the line like question random people or just in the worse case scenario take you to the police station for suspicious behavior.
Nah taking strangers into your house is an extremely intelligent idea, other great ideas include but are not limited to: following strangers into dark alleyways, accepting food and drinks from strangers, going into strangers houses, signing papers before reading them, giving away bank account information online, clicking on random links you see, and getting in white vans with tinted windows.