Classes in book 4

[FirstGenesis]

How do you get the flame sorcerer the viper sworder and trapper classes for hikaru shizuka and kurumi?

[RazorclawX]

Activate a certain number of Obelisks (Kurumi only needs around 3-5, Hikaru 5-7, Shizuka 5-9 of them).

[FirstGenesis]

Are you talking about the obelisk optional quest?

[RazorclawX]

Yes.

[GeorgiPeev03]

Activate a certain number of Obelisks (Kurumi only needs around 3-5, Hikaru 5-7, Shizuka 5-9 of them).

Alright, so am I getting this right - I could see three classes for kurumi, two for hikaru and one for Shizuka, does that mean I had activated 6 obelisks? And with the 7th I should now have unlocked third class for hikaru and second for Shizuka? Because I did replay a stage I was sure I hadn't done the obelisk at and got 7th, viper sword unlocked for Shizuka but hikaru remained with two available classes.

Also, does picking a certain class have an effect on the story and/or on the missions we get, who we side with, etc.?

[RazorclawX]

It should roughly be the case.

The class thing is mostly a gameplay choice. Only certain ones change the story (it's mostly Shizuka and it's immediately obvious which one it is, although for the most part events will play out the same way anyway and she just behaves a little more sultry)