How many hours is a bento really safe at room temperature?

Hello! I'm really new at making bentos, and the thought of leaving my bento out of a refrigerator makes me a bit nervous, and I wanted to ask your thoughts. You see, I have to leave my house very early in the morning (around 5:50 am) to get to work on time during the summer, and I typically don't eat lunch until 12:00. I'm worried that leaving my bento out of the refrigerator for 6+ hours would be unsafe, but the thought of eating ice-cold rice from the fridge isn't exactly appetizing to me either! :\ I know I could pack my bento in a microwave-safe container and nuke it, but I much prefer my food at room temperature anyway. Could I maybe leave my bento in the fridge until an hour or so before I'm ready to eat it? Or do you think rice/cooked chicken or fish/etc. would be safe at room temperature for that long?
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