DISCLAIMER: This picture was NOT DRAWN BY ME! It was purchased as a commission from an artist who has requested to remain anonymous.
This one requires a bit of explanation...
Esmeralda, Nanako and their friends all share a house together and, being the gigantic nerds that they are, frequently take advantage of their close proximity to play a D&D-style fantasy RPG, wherein they have all manner of zany (and oftentimes pneumatic) adventures.
While Nanako serves as the party's sorceress, Esmeralda - being the shy, gentle soul that she is - assumes the role of the group's healer, avoiding direct combat while using divine magic to protect her friends, heal their injuries, and disorient their foes.