Responses
The 2couple and the main picture are from the same story and author. And it looks like it from CJ Mishalski (author) but I couldn't find the manga so I suppose it's not translated yet.
Same, the little pic is the same as the first one. As for the main picture, looks like Yukimura's art. Then again, I couldn't find the manga. (︶︿︶)
http://www.mangago.me/read-manga/ore_no_ushiro_ni_tatsu_na/mh/manga/ore_no_ushiro_ni_tatsu_na/v01/c006/1.html/pg-4/
(I want 3 of the pictures couples, the important ones are the small picture (2 couple) at the top corner and the main picture couple)
http://www.mangago.me/read-manga/ore_no_ushiro_ni_tatsu_na/mh/c005/4/
(I think the 2 couple in the same picture are the same as the previous one but maybe not? Finding that and the other couple)
That small picture at the small corner of that 1 guy if possible to identify)
http://www.mangago.me/read-manga/ore_no_ushiro_ni_tatsu_na/mh/c003/4/
http://www.mangago.me/read-manga/himegoto_asobi/mh/v01/c001/8/
(The picture at the corner left)