>>280051520
Astarotte looks so natural in that style that I'd believe you if you said it was originally Harada's manga.
I couldn't find anything else with those two together unfortunately.

Here's a cool one. It has Harada and Hamada (Tsugumomo) together.
https://exhentai.org/g/1079749/2ebbc3d7e1/
Makes sense Harada likes Keio Yuugekitai. There are obvious parallels between Flonne and Rami.