If it wasn't Leng Zhiguo, then it must have been Madam Leng Wang Xiaofang who arranged this, as only she had the connections to recognize the young girls in Kyoto.
Han Dongchen had monopolized the resources designated for Leng Zhiguo's younger son. Although he had the ability to have them reassigned within a year or two, they surely wouldn't be from a local school in Kyoto, and moreover, he was returning with a promotion.
Even though not comparable to Han Dongchen now, being under thirty and Fourth grade...and truly from a schoolyard in Kyoto, this was still a very formidable character.
However, Su Xiaowan didn't know much about this man. If it was a bride found by Leng Zhiguo's side, it would have been acceptable, but if he had managed it himself, collaborating with his mother, Su Xiaowan had to be more cautious.
