he*
Shinobu's makeup design is exaggerated because the makeup is a reference to how Asians view heavy makeup. A lot of Asians, especially older generations, associate heavy makeup with a flashy lifestyle.
I've experienced it first hand with my mom. She believes that some lip gloss and a thin line of eyeliner on your upper water line is all a "good girl" needs. She'd give me lectures about my lifestyle choices if she catches me putting on mascara or eyeshadow. I bought a red lipstick once and she kept trying to hint to me that red lipsticks are for girls who aren't virgins anymore.
It's kinda unfortunate that makeup doesn't really go well with Japanese artstyle. The features of characters are expressive and unique, so make up can't be applied on them the same way it is done with real people. Especially the lips and eyelashes. Naturally, it's just a few lines on the face of the character so the way they exaggerated it with Shinobu just makes it look bad. Aside from that, the story itself is amazing and it's tips are real. It's just that it would look better if the artstyle allowed to make up to naturally work with the face. (Like if they gave the characters lips instead of just a single line)