I tried it a bit. I haved bother translating but basically, from what I see, you dive into ... um, a dream world fighting enemy.
There are 4 battles phase and in which you get to attack depends on your character. Mei Ling only get to attack in the first and one of the last.
To dive, you need to spend hearts but eventually you'll run out of them so you must then reload which gets you to a different team.
There a search option which net you character and ... um, upgrades points? Each section gives you different characters.
1st one you have to wait for 3 minutes, second one (human village) is 15 minutes. Also, each section have a % rate to show how much stuff you found.
You can only search one place at a time.
Each characters has severals pages. You unlock them by doing fight, battling with certain characters, going deeper and so on.
Fulfilling the requirement unlock a page of story.
Um... I guess that's it for now.
Ah yes, you can only upgrade so much withouth reloading.
Dive as much as you can/want and then reload. Good luck. ^^