Obento help

Leftovers from dinner will be put into an obento. DH leaves for work at about 7 am. He doesn't eat lunch until 12 noon. There is no microwave at his workplace to reheat the food. Is it possible then for him to bring an obento without it spoiling? Like if we reheat it just before he leaves for work? I learned from school before that 2 hours out at room temperature is maximum, but in hot weather, even that may be too long. But DH insists (He says with emphasis, "Zettai daijoubu!") it should be fine.

I seem to recall all my school obentos (the same time period was involved) was fine not being microwaved, and often wasn't even refrigerated. I ate the rice at room temp, the veggies were cooked but cold and most times the protein was either tofu or kamaboko. Sometimes I had those red sausages that didn't need to be kept cold to remain safe to eat.

Here's a fun website with obento ideas, lol!http://www.annathered.com/

When putting cooked food into bento box, please make sure it is cooled well enough.
If you put hot rice in the box, leave it for a while without putting a lid on till it gets not hot/warm.

Putting hot food into the box and keep it for hours does make the best condition for germs to grow, i.e. the food will be damaged.

In case of putting leftover from the previous night meal, it also depends on how you keep it.
If it was kept in the fridge, you can just put it into bento box.
If not (i.e. kept in the kitchen in a pan etc) reheat it to kill the possible germs and cool it down before putting into the box.