While visiting Japan last year, I have witnessed a scene when one of my companions forgot his wallet, which also contained an expensive smartphone, in a train,

While visiting Japan last year, I have witnessed a scene when one of my companions forgot his wallet, which also contained an expensive smartphone, in a train, when we have changed quickly the trains, and someone from the other train ran really, really fast, to catch us in the other train and give the forgotten wallet to its owner. Than he ran equally fast to his train, which was ready to leave. Had he not run so fast while returning the wallet to its owner, he would have lost his train. Therefore, doing a good deed had required quite an effort for that Japanese, but this had not dissuaded him.