From Pink Cherry Blossom Scans:

With a letter as his guide a young man named Rui visits Rio. “I thought that you’d be crying by yourself”, he says as he caresses Rio’s cheek as if he was wiping away his tears. Although bewildered by Rui’s actions initially, Rio soon realizes that he has been saved by those actions and from some point has started to look forward to them...

Summary from Renta!
The moment Rio meets the boy with the grey eyes and gets kissed by him, he knows that his life is going to change. With a letter in his hand, Rui comes to visit Rio, worried that Rio might be feeling lonely and sad. Rui touches Rio's face as if to console him and kisses him again and again. At first, Rio is confused by the kisses and doesn't know how to react. However, as days goes by, Rio realizes that Rui's desire and kisses are actually bringing him comfort.