I was thinking the same! Even at the first page it's already evident: upper left panel.
 http://www.mangago.zone/read-manga/shitsukekata_nijuumaru/mf/v01/c001/2/                                            
an assistant can copy someone elses art like that?
Rather than intentionally copying, I think it's more like they see that author's art so often, and they draw for that author according to the author's preference, so over time their art style changes to become similar to the author they are helping out with?

		
This manga has a very similar drawing with Sakuraga Mei's works, but still.. This is a great one! I love how they push and pull and in the end make out a bit. I need more chapters ASAP!