I'm in Love and It's the End of the World #3

Gloomy young Mahiru Yanase may have grown up in her twin sister’s shadow, but before the bell rang on the first day of class, the handsome Aoi Satomi had already asked her out! Mahiru doesn’t know how to handle it…but as it turns out, she had come to Aoi’s rescue years before—and he’s had her on his mind ever since! Aoi’s frank manner wins Mahiru over, and just like that, they’re dating! Mahiru isn’t exactly confident she can be a good girlfriend for Aoi, but she finally works up the courage to tell him she wants to get to know him better…so he invites her to his house! In Volume 3, Mahiru and Aoi’s romance kicks into overdrive!!