One of Masato’s lines in Shining Live is roughly, “Are you cold? I should knit you a scarf to keep you warm.”  I’m just saying, he climbed to the top of a mountain with Ai. He’s a pretty thoughtful guy and I’m sure he’d wonder if Ai would get cold. An ombre scarf that fades from lilac to dark blue and is then embroidered with Ai’s name would be a really thoughtful gift, also to commemorate climbing the mountain together. Ai would be so confused on receiving it because he wouldn’t get cold, also why would Masato go to such lengths in such a short period to make him feel comfortable? (Even though Ai, in canon to the event, brought an oxygen mask in case he needed it..) Just imagine the most in-depth, deep conversation between the two of them as Masato takes the time to explain (we know how much Ai likes to learn so this would mean a lot to him, even if Masa himself doesn’t really know that yet) how gifts are from the heart and are an extension of someone’s feelings and thoughts toward someone else. Ai might’ve thought it practical, but he was thinking of Masato in bringing that - just as he was thinking of Ai in bringing the scarf. It turns out neither of the items were needed and in a way, they can turn into sentimental items because they will always represent a memory of a moment the two of them shared.