Hard Water Stain Remover - Tera Cleaner Yamato EX - Commercial Use - Small Size

I purchased this on Mercari and used it, but the cleaning power was too strong for my household. I won't be using it again, so I'm offering it for sale.
Please check the remaining amount in the photos.
One bottle is unused, and the other has had about 10ml used.
The following is quoted from the original seller:

I am offering a portion of the hard water stain cleaner, Tera Cleaner Yamato EX.

*This is the undiluted original solution. It has not been diluted.

200ml (2 x 100ml bottles)
*A small amount has been used.
*The bottles are made of polyethylene with inner stoppers for safety.
*Labels have been attached for careful management and peace of mind.

(Will be shipped via Kuroneko Takkyubin Compact.)

How to use:
① Pour the cleaning solution into a small bottle or work container.
(For stubborn stains → undiluted solution)
(For light stains → dilute 2 to 5 times)
② Apply the cleaning solution to the area where you want to remove water stains.
(Ensure the cleaning solution is applied evenly to the water stains.)
③ Gently scrub with a toothbrush or sponge.
(Do not scrub with strong force; gently scrub to allow the cleaning solution to penetrate the water stains.)
④ The water stains will chemically decompose, and foam will appear.
(To allow the new cleaning solution to penetrate deep water stains, reapply the solution and scrub gently.)
⑤ After about 3 to 5 minutes, rinse with water.
(If there are any remaining water stains, repeat steps ② to ⑤.)

The key is to gently scrub to allow the cleaning solution to penetrate the water stains, rather than scrubbing hard to remove them.
*Please test in an inconspicuous area before use, as it may affect the material.

I have used high-quality bottles and taken the utmost care, and I believe there will be no leakage. However, I cannot guarantee against such issues. Claims to the manufacturer will not be accepted. Thank you for your understanding and purchase.