Yes, it's crystal clear but there's also this thing that Mei saw in Naru's picture with his brother. It happens in a lot of mangas and I dont wanna think bad but Did Naru feel fraternal or romantic love toward his stepbrother? And Mei said so when he says if this is cause he's his brother's son. Tell me if I misunderstood.
Naru is not blood related to Mei. I think he was the son of the mistress from a previous relationship (I think - gonna have to go back and re-read it - but for sure not related). Naru seems to feel both fraternal and romantic love for Mei (convo with friend from other manga), but is determined to be his uncle - Naru wants family. We don't know for sure what Naru felt for Mei's dad, but it could go either way. I think it's fraternal - admiration and love for an older sibling... hero worship in there as well? There was a big age gap between them... This last chapter, I think, got the ages wrong - Naru was telling a story about being in uni abroad and meeting with his brother, then said that Mei was 2, but previously we saw Naru in high school when Mei was trying to tie the prayer to the tree...
I just saw from the previous comments that they thought Naru is using Mei to hog his inheritance , when in fact, he was just hiding Mei from his greedy uncle coz once that they learn of his existence, they'll do everything to exterminate Mei.
It just showed in this latest update. Gotta read every dialogues. Don't just skim over it. Srly.