The first official Touhou webcomic, penned by ZUN and illustrated by newcomer Ginmokusei, stars Satori Komeiji as the master armchair detective hailing from the depths of the Earth.
The first issue is currently available for free on the official Touhou web blog: https://touhougarakuta.com/comic/touhouchireikiden_1/
(Source: MangaDex)
Also if you think about it the sister could have the brother to herself if she gave up her murderous tendencies and just acted regular when she reincarnated again. Also why tf would the goddess reincarnate her in the same world as him in the first place and if this is going to be a trend of her reincarnating as someone new each Time this is also missing the mystery tag.
Its been nearly 5 years since I read this, and I still think about it sometimes