みぽりんが愛里寿ちゃんちに遊びに行ったら何故かいるお母さんと愛里寿ちゃんのお母さんが大洗制服を着てはしゃいでるとこを目撃した時に照れ隠しでなんか言ってきた時の絵です

It's a picture of Miporin, who went to play over at Arisu-chan's, and witnessed their mothers wearing the Ooarai uniform and frolicking for some reason, who then said something shylike once found out.