Qinghe has a twin sister Su Qingzhi who is not close but loves each other.
Shen Yimo, a young friend who is rebellious and has a common secret.
Lin Zhimu, a family friend who has the halo of being a male protagonist.
She could have had a bloody Mary Sue story about fighting for a boy with her sister, but she never cared about it. Only the person she met later could break her heart.
The wall is so airtight that only light can shine through.
And summer is that light.