Marriage Toxin manga volume 6 features story by Joumyaku and art by Mizuki Yoda.

The epic battle between Toshiro Dogo and Gero is finally reaching a climax! Though Gero has unlocked his ability to unleash one of the Poison Clan's most powerful techniques, this fight is quickly becoming the fiercest he's ever faced. But Arashiyama is still trapped by the Beast Master, and now there's an unsettling figure closing in on them… Does Gero have what it takes to beat Toshiro Dogo and save the day?!