Both manga deal with our MC's sudden and ofc, very shocking ability to time travel (which is very conveniently never elaborated on). The MC ends up falling for his relative, and both manga have no qualms exploring incestuous relationships in detail.
Written by the same mangaka, both these manga exist in a world where the impossible is possible - ghosts, spirits and curses make their presence felt. Not to mention a romance happening between a light haired and gorgeous gay man, and a dark haired and originally het dude.
Both manga deal with the issue of time travel, which, incidentally, is used as nothing more than a plot device. Both the MCs travel back in time and through this time travel, they are able to solve the riddles regarding male members of their families, which had plagued them for long.