I recently read an isekai manga where the MC invented some stuff but wanted to be an adventurer. I remembered he invented a hot bath system, paper, etc.
I think in the last chapter, he was asked where he got the ideas or something like that, and he just said "I just point out what I feel need to be better, the works are all being done by the workers" and he proceeded to say the most advance carriage he rode in sucks and hurt his butt even though it is the latest model, which made the noble/rich guy angry. Then he proceeded to tell his friends about how to improve the carriage, such as changing the leaf spring into helical spring.
What is the title of this manga?