[Balzac]

Originally Posted by bahamut zero

but I thought she also appears during the common route in EX, no?

Spoiler for Saya:

Yes she does. like any other capturable heroine - albeit only after clearing Refrain. Now, the requirement for even seeing her in common route is for the player's benefit, as one goes into Saya's, Kanata's and Sasa-chan's route with full knowledge of Refrain. But in the "timeline" so to speak, Saya and Kanata are before Refrain, while Sasa-chan's after. (Though apparent canonicity's as to the latter is up for interpretation - this would put Sasa-chan as the girl who ended up with Riki in the end.)

Edit: 10/06 - As an addendum, the timeline also implies that

Spoiler for EX routes:

Kanata's occurs after Haruka's route, chronologically.