For that you need to learn how to draw a simple cube first. Get some boxes of any size and sketch them, also if you have some anime figure draw it from any view point!
Yes it is, too bad that Shaft ruined her arc with bad animation. :notagain:
, make it a B cup if you want. (JUST NOT FLAT! ;_; ) We are standing directly in front of said sister, maybe 1-2 feet away from her body, ~inches to 1 foot away from her face. She is looking up at us (in one version) or is looking down at her textbook (in another version), I can't pick. The textbook is on top of the table below us, and (due to perspective) is quite a ways away from us visually. But you can make out some of the pictures, barely: it shows people having sex, maybe a vagina, maybe a penis, maybe a condom or a dildo. The girl's breasts are smushed together a bit, accentuating her cleavage, because (Version #1) of the placement of her hands on either edge of the textbook, fingers pointed out to the walls of the room (i.e. 180° from the center of the book), or because (Version #2) one hand is leaning on the table while the other hand is pointing to one of the pictures, and the way in which she's doing it is using her upper arms to squish her boobs a bit. Either way, there's a speech bubble (or a caption, take your pick) in which she asks, "Onii-chan, can you teach me about sex?" (or some such). Top garment is a thickly-saturated, bright-luminosity pink. Bottom garment (say a casual skirt for wearing around the house) is sky blue. Hair color, length, and style are up to the drawer. (I pictured medium-short [i.e. reaches the nape of the neck] with two side ponytails, each of which is tied up with a scrunchy that has two cherry-sized balls to it.) The point is! You should never be low on ideas! That's blasphemy! And the reason I'm posting it is because it's so fantastical (i.e. fiction, fantasy, whatever word you want to use) that it drives home the point that the sky is the limit when it comes to hentai! 
