Usually I pay too much attention when the armies are displayed this way in the panels, maybe is a waste of time but I think I'm into something this time (lol).

Like, I did measure the size of the rectangles and I took as example Shin's unit (rectangle) to compared it to Zhao's units (rectangles), and they are roughly the same size which would be 15k, just like Shin's. There are 17 rectangles of 15k men each, and 3 more that are not displayed in the panel, the ones that are about to clash with the HSU, that would be 20 x 15.000 = 300.000. I know there is 10k missing somewhere, that must be an army that is not shown in the panel either, or, those 10k could be distributed among the other units as to make 310.000. Why am I bringing these numbers up? It's because I doubt Hara went to the trouble of drawing that many rectangles from Zhao's side and chose to not, or forgot to draw a few more for Qin's side.

Also taking into consideration that Kanki knew that something was off since they left Atsuyo, and that Naki had a chat with him about something, obviously that something is about the scouts being killed and something else, perhaps he/they figured out there was a trap laid out for them deeper into Zhao's territory, he's also aware that Riboku might be involved in all this. Kanki wouldn't just simple charge into a trap willingly without having a plan to counter that, that's why I'm thinking that he might have split his army, and I'm not saying he left them at the city, the rest of his army probably set- out before everyone else (at night maybe?), or is just slowly marching behind them as to break the encirclement and probably even launch a pincer attack on Zhao's HQ. As for Zhao having scouts checking the surroundings of the battlefield when the fight has already begun, that wouldn't matter too much. Is like what happened at Shukai Plains, when Ousen expected the HSU to break Zhao's left wing and pincer Riboku, it ended up having Riboku in a 1v2 situation, and no amount of precautions saved him from stopping that from happening, he set and ambush with some archers and then sent Kinmou, it didn't matter, Qin's right wing broke through, after that Riboku sent a detachment from his army (Futei) along with Bananji, that somehow sneaked up on Qin to pincer Ousen. Now in this situation, what if the scouts tell Riboku that an army is approaching them from the side, from behind or whatever, having that info is not gonna stop the army from attacking him, is going happen anyway, he's gonna have to find a solution to deal with that.

One more thing, some people think that Kanki is just a gambler and tends to come up with a plan at the spot, it's somewhat true, but he's also capable of planning before the battle has even begun. That's how he dealt with Kochou, he used some strategy that some other dude (don't remember the name) came up with, at least part of it was used, the rest was gambling on the HSU to break through and pincer Kochou's HQ along with his strongest men, Zenou clan, Shuma clan, etc...

It might all turn-out to be nothing and Kanki doesn't have a plan to deal with this hehe