About last panel that kid looks like kagura but she wearing kimono, not chinese dress, so probably not kagura kid.... maybe its tsukuyo, sacchan or madao kid
(Another route, it can be bansai and otsu kid, to make shinpachi on agony lol)
The more theories and shitposts come out, the more I think that this troll timeskip(I think the flashbacks are real) the more I think Sachi has something to do with this lolol
like maybe since he was free during the invasion he could observe and as questions of what happened during the war, while the flashback is a troll since he would back at prison most likely(so he has to make up the ending/timeskip)
and Sachi has ties to Katsura and Gintoki(so he can get the truth from the space side from Katsura, and the truth on the earth side from Gintoki)
That little girl in the end of this chapter, she is too old for a time skip of only 2 years to be Shinpachi's... so maybe she is the daughter of Madao? Since she mentioned "that man with glasses... my papa?" can also apply for Hasegawa (and he is old enough) lol