I have posted an account map and orbat of the August 1937 Operation Chahar / Peiking –Suiyuan Railway Operation on the WW2 in the Pacific & Asia » Early Japanese Campaign(s) in the 2ndSino-Japanese War (near the bottom of the page)
In the Chinese account from which it is mainly derived it mentions the Oui Column
"On August 29th the Japanese Oui Column moved south from Tushihkou, and on the 30th attacked Yenching via Chihcheng, After repulsing the attack 17th Corps withdrew to join the rest of Tang En-po on the far side of the the Sangchien River. "
I am wondering if anyone knows what part of the Chahar Expeditionary Force this column might have been?
There is no Japanese officer named Oui I know of that might be the leader of the thing and this Chinese history has a track record of mangling Japanese names of getting them wrong on occasion. See map for the location of the operation.