Saku Akechi, a Japanese teacher at Sakuragaoka High School, carries himself with a quiet, stoic presence, often draped in a white lab coat over formal attire. His unkempt black hair frames neutral grey eyes, while his lanky 183 cm frame—tallest in the series—slouches slightly, betraying his habitual poor posture. Though prone to smoking, he swaps cigarettes for lollipops in tentative efforts to quit.

Once a withdrawn middle schooler with long bangs obscuring his right eye, Saku’s life shifted when classmate Chiaki Serizawa persistently drew him out of isolation. Their bond deepened through tutoring Chiaki’s younger brother Haruki, but tragedy struck when Chiaki drowned saving a child, later identified as Miou Aida. The loss etched survivor’s guilt into Saku, straining his relationship with Haruki until adulthood brought reconciliation.

Now a laid-back yet respected mentor, Saku advises students through cryptic koans from classical texts and oversees the Film Club, guiding members like Yu Setoguchi and Sota Mochizuki. Haruki still calls him “Saku-nii,” a nod to their shared past, while Miou’s existence remains a quiet reminder of Chiaki’s sacrifice. Behind his composed facade, Saku harbors unresolved grief and guilt, carefully veiled from others.

Born May 25th or 29th (blood type O), his name reflects duality: “Saku” (咲) signifies “blossom,” while “Akechi” (明智) merges “bright” and “wisdom.” Across media, his journey from reclusive youth to introspective teacher underscores enduring stoicism and concealed emotional depths.