Responses
This is the link to the table of contents http://www.mangago.zone/read-manga/sora_o_daite_oyasumi/mh/v01/c007/4/
The table of contents is from an anthology, so it isn't from the manga itself.
If you look at mangaupdates, it says the manga was discontinued.
Also you can read here what 勇気 (Yuuki) wrote about it:
http://www.mangago.zone/home/mangatopic/833292/
Can someone tell me why this manga called dropped? I dont get it. I think this is complete manga, because it has table of contents with 12 chapter on it. (⊙…⊙ )