
There are two questions that I have:
1: Is Kiku the grandfather? I always believed so.
2: Who is the person in the last image? I mean it looks like a mature version of the kid and Kiku looks the same. WTF is happening?

I believe that was the real Kiku when he was younger. My theory is that the real Kiku was this Kiku's lover. But when this Kiku went on plane for war, he never came back because he got time slipped into future. While the real Kiku after waiting for his not coming back lover, though perhaps he has perished in war. So the real Kiku got married and his grandchild is this young guy.
While in the current timeline, his ex-lover (current Kiku) will fall in love and be together with his grandson.
Is the next chapter out yet?????? ┗( T﹏T )┛