A 69-year-old man from Osaka Prefecture filed a lawsuit Thursday against his deceased same-sex partner's sister, seeking assets left behind by his late partner and damages for being barred from attending his cremation.

The rare case involving inheritance from a same-sex partner highlights the problems faced by such couples upon the death of their partners, as legal protection is only currently provided to married couples.

The man sued his partner's sister at the Osaka District Court, seeking to win back the assets held by her following her brother's death in March 2016.