Hitsuji no Kawa wo Kita Kemono

When Daichi learns that his older sister is engaged to Jun Igawa, his initial reaction is far from celebratory. Jun is undeniably striking—wealthy, accomplished, and effortlessly charming—but these very qualities only deepen Daichi’s unease. He cannot fathom what a man of such extraordinary caliber sees in his ordinary sibling. The disparity between them feels too vast to be genuine, leaving the younger brother trapped in a quiet storm of doubt as he scrutinizes his sister's seemingly perfect fiancé for any hidden cracks in the facade. Despite his lingering suspicions, Jun proves difficult to resent. Every interaction reveals a warm, considerate nature that slowly begins to dismantle Daichi’s defenses. As the days pass, the protective brother finds himself reluctantly lowering his guard, drawn in by Jun’s impeccable manners and gentle demeanor. Yet, beneath this polished surface, an unsettling question continues to haunt him. Is Jun truly the flawless gentleman he appears to be, or is his kindness merely a carefully constructed mask? Daichi is left to wonder whether his sister has found her dream partner, or if she is unknowingly inviting a devil in disguise into their home.