My Younger Brother is Really Big, Wanna Come See?

Living a pretty ordinary life, preteen boy Nao has his routine upended when his older sister Chiaki catches him in an embarrassing moment in the bathroom and notices something unexpected. Rather than letting it go, Chiaki pulls out her phone and starts texting her friends. By the next day, two girls named Nagisa and Yukiko are showing up at the house, curious about what Chiaki has been hyping up. That's basically the entire setup of this 2-episode OVA from T-Rex, and the series leans fully into the awkward, shameless comedy of that premise from there. The tone is lighthearted and plays the situation mostly for laughs and escalating absurdity, built around the interactions between these four characters in a domestic setting. The character designs are distinct enough to give it its own personality within the genre, and if you've already watched things like Imouto Paradise! or Aneki no Kounai Kaikinbi and are looking for something in a similar wheelhouse, this fits that same general space. Fans of Oni Chichi will also recognize the family-adjacent dynamic, though this one keeps things a bit more grounded in a single-household setting rather than sprawling further. At two episodes, it doesn't overstay its welcome. It's a short, self-contained adult OVA with a simple premise it commits to without much pretense. You know exactly what you're getting from the title alone, and the show delivers precisely that.