Postcard From Japanese Invasion Of Manchuria

Here's a card I picked up a few weeks ago. It's a Chinese-made card of some Mongolian locals outside their ger (with a few western-style tents too). It was sent by a Japanese soldier called Gisuke Satou to his sister called Teruko Miyoshi, probably during the Japanese invasion of Manchuria in 1931 although it's undated as far as we can see.

I asked someone to translate it, which turned out to be trickier than expected. It uses all katakana (the style at that time) with no Chinese characters, as well as some old katakana ('we' which has been replaced now with 'e'). Here's as much as we can translate (anybody out there able to help fill in the gaps, and the meaning of the red banner cancel which looks Chinese rather than Japanese)?

Dear Teruko-chan
How are you?
(Something about listening obediently to fairy tales told by mother and father)
All we eat is Taro Potatoes here to stave off the hunger. I'm being careful, because if I make trouble, or cry, one of the old senior officers will come!
Sleep well, Te. I'm sending a letter to Numata. Take care big sister.
Farewell

What a lovely insight into the life of the ordinary Japanese soldier, who was just as miserable as any other soldier.