En Yufuin is a third-year student at Binan High School, standing 183 cm tall with dirty blonde hair and blue eyes. His personality is inherently laid-back and unhurried, embracing minimal effort in daily life. Yet, this tendency toward slothfulness gives way to reliable leadership when situations demand focus or decisive action; he steps up to guide others effectively during crises. He shares a close bond of mutual trust with Atsushi Kinugawa, using the nicknames "Enchan" and "Atsushi" despite their contrasting temperaments—his relaxed nature opposes Atsushi's serious demeanor. He transforms into the water-affiliated Battle Lover Cerulean, wielding the "Purifying Aqua" love stick for his attacks. His full transformation title is "Flashing Prince, Battle Lover Cerulean." Personal preferences include a fondness for hot springs, seafood curry, and manju, while he exhibits a strong aversion to cockroaches, reacting with visible panic upon encountering them. His birthday is July 2nd. As a member of the Earth Defense Club, he collaborates with Yumoto Hakone, Io Naruko, and Ryuu Zaou to protect Earth from threats. This commitment extends into new conflicts, such as confronting the antagonist Deathamor in the 2025 storyline, where his reunion with the club underscores his ongoing dedication despite his typically easygoing disposition.