yokubou pandora
English name 'Desire Pandora'. A "extreme ecchi" manga by Hizuki Akira. It started publication in Issue 8 of Comic ExE (July 25th 2017), which is a hentai magazine, before being transferred to Cmic MeDu.
The story centers on Takai Tsukasa, who has an armpit fetish and lives next door to Chika Hasumi. The demon Roselia appears before him one day and then basically it's just a fetish fantasy about armpits.