two comments below you have your answer
Ohh okay, thank you!!
Nope, i still don't understand, sorry. I got that he pretended to leave but just did it to test the other's feelings and ive read the other stories before (might have forgotten but), but I still dont know who that was on the last page. the only people i can see are the uncle or yada (but isnt yada like...dead...) ^^" I think I'll clarify and add a link to the page it was on. thank you for trying though!
It's Yada. I think that extra chapter is the story afterwards.
http://www.mangago.me/read-manga/mizu_numuru/an/mizu-numuru-chapter-5.html/34
The guy on the very top left--
Was that one black haired guy on the street that turned around to look at ayu and naoki an introduced character? It seemed like he had something to do with the story (kinda looks like that uncle from the first story?) but idk