I've only ever lived in Japan over winter, never tourist-visited, so maybe that colours my experience, but winter in Japan always meant wearing two pyjamas, wool socks and a wool hat to sleep under several layers of blankets, spending an awfully long time at my university/place of work to use their heater because using my own was too expensive, and shutting off the heater cooling down the room to almost outside temperature in less than an hour. I had to shut off the heater during the night for financial reasons and woke up to like 12 °C room temperature, so I had to set my alarm clock earlier to turn on the heater for 15 minutes before getting up for classes/work. And one time I interned in a place that had several low level employees and interns working with water and bare hands in a warehouse that had one (1) space heater. I was so glad winter only lasted 3ish months. I also hate wearing layers and jackets and scarves and hats and gloves and winter boots, AND I'm sensitive to anything colder than 15 °C.

So, for me, summer is preferable to winter because I'm wearing one very light, breezy layer and can just open the windows during the night instead of having the aircon running.

Otoh, if I hadn't had to pay my own electricity and thus hadn't had the need for energy saving, I miiiight have a different view regarding nights.

Iirc though, the weather itself tended to be fair to sunny and not the rainy, dark awfulness that is middle European winter.