First i was WAAAAAAAA
Then i: wait, so the series is skiping their first one...? And its done.
I guess we must accept that Rei - Hina is already a stable relationship, to the point we must stop seeking for more detail about it so much, because now Umino need to turn the plot back to Shogi, where Rei is starting to face problems.
With this kiss, we have reached the ENDGAME for Rei-Hina ship until the end of this series.
Now it is only Shogi, and if possible, Akari's spring.
Well, honestly i thought the author would freeze it when Rei said to Gramps that he would wait to make the proposal clear to Hina later. Well, he waited, like some months, lol