A Toto representative told Japanese newspaper Mainichi Shimbun that its bidet toilet seats are made of plastic resin due to the material's "resistance to detergents and its ability to be molded into complex shapes".
However, wiping the seat with toilet paper or dry cloth can cause small, invisible scratches where dirt may accumulate, leading to discolouration.
But Toto is not the only manufacturer that has advised users against using toilet paper to wipe its toilet seats.
Similar recommendations have previously been issued by cleaning experts and also published on lifestyle sites.
Instead of dry toilet paper, people recommend using soft cloth soaked in tap water or detergent. They also advise against using thinners, nylon or metal scrubbers, or abrasives - all of which could damage the surface of the toilet seat.
The company said that while it was looking into more scratch-resistant materials, "there are no plans to change the material at this time."
The Washlet, Toto's flagship bidet toilet, includes features like an automatic lid, an air dryer and pressure controls for the bidet's water stream.
Japanese toilets, with their thoughtful designs viewed as an extension of the country's hospitality culture, have become an unlikely tourist attraction for foreigners and a source of pride at home.
