四葉

Hailing from England (as evidenced by her occasional penchant for anything with a Union Flag), Yotsuba fancies herself a detective à la Sherlock Holmes. She can often be found with either a digital camera or a magnifying glass in hand, trying to spy on her brother. She refers to herself in the third-person and is fond of using the catchphrase, "Checky!" (チェキ! Cheki).

She addresses her brother as Ani-chama (兄チャマ), which is a childish address similar to Kaho's, but laced with a British accent. In English, she calls him "Brother Dearest".