The Sad Ghost asks the Hero/ine to help it find its dried rose, which was stolen by a monster. The Hero/ine must then slay enemies at the same depth until s/he retrieves the Dried Rose.
Every time an enemy is slain, there is a chance that that enemy drops the rose; the drop chance is 1/(8-n), where n is the amounts of enemies slain since talking to the ghost at the same depth. Thus, the Hero/ine must slay, at most, 8 enemies.
Once the Dried Rose is given to the Sad Ghost, the Hero/ine will be rewarded with the choice of either the Ghost's weapon (melee), or the Ghost's armor.