They named their daughter Tora and as she grew so did the stone. Tora eventually became the concubine of a warrior whose life was saved by the stone. When an assassin came for his life the stone transformed into him and attacker mistook the stone for him. All of his attacks bounced off the stone.

The Torakoishi is based off a stone called the Toragoishi. In the legend and old samurai and his wife were unable to have children so they turned to the goddess Toraike Benzaiten and she blessed them with a stone. They worshipped the stone and soon they became the proud parents of a daughter.

Reasoning:

1) Akaname appears in dirty tubs and licks them clean. Roaches go to dirty places to clean them.

2) Akaname’s saliva is toxic and can spread disease. Roaches carry diseases.

Origami design by Origami Dachan on YouTube