
April 26th, 2032 A.D. - Megalopolis Tokyo - 00:12 in the morning A total lunar eclipse occurs for the first time in 3 years. Even though it's supposed to be a simple astronomical phenomenon, it soon sets off a series of unexpected events. Unexplainable mysteries, terrorist incidents, and network crime surge as if in unison. The truth mixes with lies, as if the world is awake but still sleeping. Something has begun. Somewhere no one can see. Something no one knows about. This is a story of the chance meeting and tragic parting of the young men and women living in this world. Players get to play the game from 4 different points of view: Route A - Hinata, a youth who has lost his sister and himself. Route B - Ishtar, a freelance programmer and leader of a hacker team. Route C - Ishtar, but seems a bit different from the Ishtar in Route B.... Route D - He, a man completely shrouded in mystery. And thus.. "The beginning is the end, and the end is the beginning"
I/O is a Japanese visual novel of 808,686 characters, with 22,056 unique words and 2,433 different kanji. Its difficulty rating on Jiten is average, 2.9 out of 5. The full vocabulary list ranks all 22,056 words by how often they appear, and you can study them on Jiten or download them as an Anki deck.
Here are some of the words that appear most often in this media, as well as a sample of its rarer vocabulary.