Heiko- Into the parallel worlds

After the suspicious death of his dad and the mysterious disappearance of his mother, Riyoko has been living life as an empty shell, feeling like nothing matters the same way he feels about himself. Feeling like he has nothing while also doing nothing, he somehow has a weird feeling, as if he was waiting for something to happen. Then suddenly, Riyoko encountered the ability to travel worlds, where he met a girl who proclaimed to be his so-called cousin from across worlds. A life-changing meeting where he soon finds out that his ability and his so-called cousin are somewhat related to his parent’s incidents, how are they related? Will finding out be for the better or not? Riyoko, who’s trying to find his purpose in life, will he have the will and determination to find out?