What crysta can be fit in second slot?

I'm kinda new to the game pls be gentle ;-;
edit; the first crysta is stellar ooze II

 

I don't really play katana that much but.. Lilicarolla should be a good crysta if the class you're using is katana. It gives +18% Unsheathe Attack. Base crysta is> [odelon machina] > upgrade crysta> [tappler] > upgrade crysta> [lilicarolla]. The price of all of the crysta combined should be around 5.5m to 6.5m at consignment board. Specter of death should be a good alternative if you're at a tight budget only cost 1.2m to 1.6m it has the stats; Unsheathe Attack +10% Accuracy +15% Aggro -20%
I hope this helps ^^