Aye, the SD2 Virtual Console port is something to get giddy about...I thought it was a good indication that we might see an official SD3 release, but that's just me.
Anyhow, yeah, the staple of the Mana series are the Mana Tree and, to a lesser extent, the Mana Sword. They recur in just about all the games released so far. But if you're gonna do a fanfic, try putting it between SD3 and SD2--those are easily the hallmarks of the series.