The story of 'Aisai Nikki' follows the sexually frustrated husband, Keisuke, who can't get it up for his beautiful wife, Sanae. Tormented by his impotence but desperate to see his wife dripping with pleasure, he makes a degenerate proposal: he asks his subordinate, Ryouichi, to fuck his wife senseless while he secretly watches. The arc begins with Sanae's initial hesitation giving way to raw lust as Ryouichi's thick cock stretches her wet pussy. Keisuke jerks off furiously from his hiding spot, watching another man pound his wife, filling her womb with load after load of hot cum. Sanae, discovering her inner slut, eagerly takes Ryouichi's cock in her mouth and ass, moaning for more. The climax of their diary of depravity is a filthy threesome, where Keisuke finally joins in, double-teaming his wife, covering her face and tits in ropes of cum alongside her new fuck-buddy.