Setsushi is rather surprised at Mizuki's request. He wonders, to himself, what sort of hunger could drive a person to apply as a domestic servant at such a modest residence...! But keeping those thoughts private, he transmits feelings of concern; "If Madame wishes to dine, she is welcome," he says. Though his words are brief, almost curt, they are accompanied by many layers of submissive, polite projected thoughts: assurances that he made too much and will happily share, hopes to be of service to these strangers, and caveats that he is not a very good cook, and the meal may not taste very good. sweatdrop
He extends the invitation to Lysa, as well; if she isn't in any hurry, she is welcome to stop and partake. Setsushi is a new resident in this place, and would be very pleased to establish ties with the local people.