There are some sources of exp in Pockie Ninja. The main source of exp is from Hall Training and you can do it offline. Here some easy ways to level your ninja.
For early level (1-15) what you really need to do is following the quest. The exp reward will make you level up fast. Remember to accept all quests first then do the [Main] quest before the other [Branch]. There is some [Tutorial] quest for newbie, read it carefully. On early level you can leave the My Village quest.
2. Chain Attacking
Before level 31, drain your movement points (yellow bar) here. Chain Attack the highest level monster in the highest level map that you can access. Instant finish it using your coupons. You pay some stones to start chain attack. Instant finish needs 1 coupon for every 5 battles. Don’t forget to claim your newbie pack in Pockie Ninja home page for its VIP Card. VIP Card will earn you more experience and movement points. You should also buy the EXP 2x Seal in Item Mall.
3. Hall Training
This is your main source of exp starting from level 31. You can do this offline. The best place to hall training is in the Special Place (with Crown) in Special Room (+15% exp) in Angel City Hall. Everyone in your level is competing for this place. To occupy this place you can grab it from another person if you beat him/her in battle. There are only 5 free battle to occupy this place so use it carefully. You can try your build by dueling him/her first (View Info -> Duel). Don’t forget to buy the Stamp of Special Training in Item Mall to increase your exp gain here.
4. Las Noches
Las Noches give you good exp if you can reach the high level round. Monsters in Las Noches are hard hitter so better use speedsters build. If you have gold you should pay the auto-challenge, it will bring you more far than the manual challenge.
5. Demon Hunting
This is the best way to gain exp. To do this you must have Demon Proof of Suppression and fight the demon mob that spawn in the highest level map you can access. You can synthesis this Demon Proof from grenade using two 32 SV catalyst (thank to DamageInc for this recipe). Other ways you can get it from exploration. Better do this in high level when there is double exp event. Don’t forget to use VIP card and EXP Seal.
When you strong enough in arena you can reach the high rank. In the high rank you can exchange your medal with more exp. So be strong to level.
So the better you fight the better you level up. But to be strong you need gears and gold in Pockie Ninja.