To be fair, Eri is trying to convey without betraying Takamine's trust.Man, the dialogue in this chapter had like no substance. Eri just went like "I know you're not confident, but be confident" with Shirota responding "I dunno... But yeah... But no..." over and over and over. Nothing constructive was said, no progress was made. Ugh.
Eri does plainly state on the final page, "because it's you, Kou-chan, it'll be fine."