A contractor came to let me clean the sewer pipe.

The area from the public masu (the last masu to the road) to the main sewage system is managed by the city, so cleaning may be required. In that case, the Sewerage Division will contact you in advance, so please cooperate.
In addition, since it is a public masu, the drainage equipment masu and pipes on the site side will be managed individually. Basically, the Sewerage Division does not perform cleaning, etc. for a fee.
If you have any questions, please contact the Sewerage Division.