What is this stuff?

[Old Coastie]

Is this a peroxide gel, or perhaps a bleach gel of some kind?

Kitchen and Bathroom Mold Remover Gel - Japanese Formula - Wasabisix

 

[Hack Attack]

without finding a sds with a quick look

I'd say sodium hypochlorite based is my edumacated guess (3-4hrs dwell for best results) and may require reapplication