It’s a multi work and this lazy high schooler who’s sent to investigate things by a small Sherlock Holmes boy and she gets into situations like old men pretending to be yokai, an octopus and a homeless guy, a tribe that treats her and someone that was pretending to be a boy like pigs, and it ends with zombies.
This has been impossible to search but it used to pop up a ton on nHentai. There was also a ditzy friend too.