Completing scenario quests is a very important part of the game. During the questline progression, you also progress the achievement "Quest Master". In the process of completing quests, you will receive:
Stats Points
Zen
Cash Points
Boxes of: Kundun; Luck; Red chocolate; Navy candy
Levels
Jewels of: Luck; Justice; Harmony; Bless; Soul; Chaos; Life (Extra jewels for progress in the "Jeweler" achievement
Misc: Spells; Fruits; Gemstones; HRS; BC Cloaks, Kalima maps, Pendant & Ring
Items for beginners; Star of Sacred Birth, Gold Medal, Silver Medal, Heart of Love, Firecracker.