I can feel how lonley and useless the uke feels (the mangaka catched very well the mood) but for me- there is too much missing, too many open questions (why, where, when..)
unhappily you dont get more information out of the prequel: http://www.mangago.me/read-manga/yorokobi_wa_hiza_no_ue/
Yorokobi wa Ude no Naka