It’s original, according to Wikipedia, Getsuyoubi no Tawawa started as blue monochrome illustrations, to « provide a positive motivation towards workers and students alike on Monday mornings ».
That explains the color choice that surprised me at first, the images are in “bluescale” instead of greyscale. It gives a softer, warmer feeling, it’s not bad at all
Oh, as for the story. A busty highschool girl loves a lot her boyfriend and they have their first time together. Loving, caring, and copulating, this is sweet
This has been released by Mikakunin, and recommended by my friend KCZ117, thank you!