I finally got to see you again. (Ruikasa story) Kinda angst

Tsukasa Tenma is very lonely as a child, since his parents only really cared about Saki because of her condition. So, one day Tsukasa goes to the park next to his home so he can play with the equipment. When he reaches the park, he sees a kid crying. The boy walks up to him. The boy finds out it is a kid named Rui Kamishiro. The two befriend Each other and become really good friends. But one day Tsukasa must move to the US so Saki can get better treatment for her illness. Will the two boys ever meet again?