Extra commuting time not counted as overtime?

Hi, I recently started working in Japan, and on my 3rd day I was sent to visit an office quite far from the one in Tokyo where I work. Normally, it takes me 30 minutes to get to work. To go visit this other place, I had to take the Shinkansen + a bus. Total commuting time to get there was 2 hours and a half. Obviously this also applies to the evening when I came back.

I thought that would be counted as overtime (those extra 2 hours of commuting) but I got told that it doesn't. Is this normal? That is an extra 4 hours of commuting time in just one day… btw, my company is not 100% Japanese (half Japanese, half foreign, and the atmosphere is very relaxed)

by Runaway-run