After completing the main story of Jade Cocoon a new feature becomes available called The Eternal Corridor. The object of this section is to explore as deep inside as possible and test the name "Eternal". The corridor consists of randomly generated "rooms" which are made of straight paths occasionally dividing into two paths. Only one route leads to the end of the room. Once the player finds the "end" of the room they proceed to the next in the corridor. These randomly generated "rooms" supposedly go on indefinitely.
There are wild minions residing in the Eternal Corridor. Their experience level increases as the player progresses through the corridor. Their level increases as such:
- Corridor 1-4: minion Lv. 20
- Corridor 5-8: minion Lv. 21
- Corridor 9-12: minion Lv. 22
- Corridor 13-16: minion Lv. 23
This continues on and on thus making it harder to progress through the corridors.
At the end of each "room" is a "boss" minion. There are eight different bosses. Once a player has defeated each one once (and therefore completed eight rooms of the corridor) the cycle begins again, only the player encounters two of the boss minion at once at the end of corridors 9-16. Following the pattern, the boss battles at the end of rooms 17-24 have three of the minions. Because the maximum number of enemies in one battle is three, after room 24 the battles for rooms 17-24 are repeated with the only difference being that the enemies are stronger each time round. Each of the boss minions has a probability of dropping an item called a "skin" when defeated. These can be used in conjunction with minion merging to alter a merged minion's appearance.
Once the player has the ability to venture into the Eternal Corridor the shop gets some powerful new items in stock. The most expensive of which is the "icicle" sword, costing 999990 Yan.