Mûn

Mûn is a human explorer of the Interstellar Patrol.

She's a brave young woman always designated exploration and reconnaissance missions, with many friends on planets near Deiland. She's pleasant and energetic, and tries to take the initiative in any situation.

She guides Arco through the main story line, and later lets him travel between Deiland and Ankora. You can't trade with Mûn.

Role in the Interstellar Patrol
Mûn introduces herself to Arco (and later Lily) as an explorer of the Interstellar Patrol, but she seems to be a prominent member of the organization with wide-ranging responsibilities. Throughout the game she...
 * discovers Deiland on a reconnaisance mission;
 * has classified information on her ship;
 * is sent to Ankora as an emissary to Nidawi;
 * is put in charge of the investigation when Yuki commits a series of thefts throughout the quadrant;
 * tracks Goliath to the Pirate Moon and confronts him there;
 * is sent to the Demon Prince's ship on a spying mission when it begins heading towards Deiland;
 * hires Locke as a consultant on dark magic.

Expanded universe
Summer in Mara is set in Deiland's past, when Mûn visits Mara for a vacation from the Academy (see Mun in the Summer of Mara wiki). Her time on Mara is referenced by the Mara postcard item.