It takes Eiji a minute to figure out that she's not planning on paying for her lunch. In fact, it takes him until he sees his doubles partner counting out extra money from his wallet.

"Hey, wait a minute!" Eiji objects. "I'm paying for hers." He immediately gets out his own wallet and starts counting out coins.

"It's okay, Eiji; you don't need to spend the money." (The hidden implication here is extremely subtle, but Eiji does have a tendency to let money slip through his fingers...)

Eiji picks up on it, though, and rather resents it. He glares at his doubles partner. "I can pay, Ōishi."

"We'll split it," Ōishi concedes, diplomatically.

"Fine," Eiji says, but he's still pouting a little bit.