Kekkon Zenya summary:

In a twisted tale of taboo seduction, two brothers find that some bonds go deeper than blood. The night before Rikuto's wedding, his handsome, successful younger brother Takumi pays him a visit. What should have been a standard congrats quickly transforms into a night of sordid sex when Takumi ties Rikuto up and claims he'll stop at nothing to prevent the next day's nuptials! Will their union bring them happiness or leave them clawing in the darkness of despair?