To join a clan, you must ask the moderator of the clan you want to join to join. Then you will be given a passcode and banner to put in your signature! There must be something in your signature saying which clan you're from, like a banner or text. Remember clans are OPTIONAL!

Here are the following clan leaders in which you can ask.
Clan leaders on the left, the clan the clan leaders lead on the right.
[Note: Dragon Hishou is led by two clan leaders, Matt and Falco.]

SoraXKairi Fan - (Wings to Discovery)
Xemnes - (Seraph's Song)
Tenken - (Juppongatana)
Matt, Falco - (Dragon Hishou)
Xuashoj - (Subeta Doumei)
VG Freak - (Kokoro Tenshi)
Excalibur1 - (The Endless Abyss)