Panasonic Washing Machine Tub Cleaner N-W1A (1 Use) - Brand New, Unopened

Thank you for looking.
This is a new, unopened Panasonic Washing Machine Tub Cleaner N-W1A, single-use pack.
I bought this a few months ago because I was having trouble with black mold-like substances appearing every time I did laundry. However, I ended up not needing to use it, so I am now selling it.
I believe the price is lower than what you would find on online stores. Please consider it.
It will be shipped via Raku Raku Mercari便 (Takkyubin, 60 size).