Ou Sen can be cornered, but the number of people capable of putting him in that position is probably fewer than a handful.
Riboku is trash. even with 6 months of preparations blud almost died to kanki who lost his army. mf mentally overrating his dick and getting trashed in front of his own army. riboku is nowhere near of kanki's level
Ri Boku is 3-1 against Qin 6GGs. Kan Ki is 0-1 against 6G/3GH tier commanders.
The only reason his ambush worked as well as it did was because Gian was taken under Ri Boku's nose and put him in the mindset the same could happen to Hika.
Kan Ki had nothing to do with the taking of Gian, that was Shin's initiative.
It's no different than Eikyuu, where the HSA taking Eikyuu led to Ko Chou moving 5K troops and opening the window of opportunity for Kan Ki.
Ou Sen had the Q3 at Shukai but he used them with specific strategy in mind. Kan Ki only asked the impossible and expected it to happen, even when he didn't ask for it at Koku You, Shin still delivered by killing Kei Sha and effectively handing the victory to Kan Ki on a silver platter.
Kan Ki got BTFO'd this arc. Lost 130K men in a day, spent 99% of this time running and hiding, watched his officer butchered and then ended up a pincushion himself. Those are just the facts.
Wow, Shin and Mouten escaped the cage like it was nothing. Lol.
The cage cost them more than half their armies.
The encirclement cost them a bit more.
Considering there were layers and layers to the encirclement, it only makes sense it was thinnest at the border.