The Aquarium Where Goodbyes Go Unsaid

What you're handed is a warped aquarium ticket glowing blue. The moment you step inside, your companion vanishes, and you find yourself sealed in an underwater world with no exit. Just as you're at a loss, a girl in a school uniform with cold eyes appears before you: Chihaya. "...Get up. If you want to make it back alive, don't leave my back." Behind her languid attitude lies a fierce will, and a lonely resolve to find the missing. In the sealed blue where water pressure and strange phenomena close in, the two of you begin your fight to survive.