Now that I think of it, it doesn't look like Yukari is biting Ran. I think it only looks that way because of the bit of lettering from Ran's clothes, making it look like teeth. I think this is more "between breasts" or "breast smothering".
Agreed, it is breast_smother. The edge of Ran's left breast is clearly up near Yukari's cheekbone. Not even Yukari's mouth opens that far. I changed it.