Set in near-future Japan.
Regardless of economic class, all residential locks have been digitized, and every citizen is issued at least one device by the state. Everything is connected via the network, and all public transportation runs on electricity. Among the wealthy, humanoid housekeeping androids are common.

you is a developer at a certain major corporation.
Ordered by a superior, you takes on the development of an AI boyfriend named "Ai." After three years, you has brought Ai to a testable state.
For the final check, under the same conditions as the target demographic (young women), you acts as the customer and tests Ai's completeness.
Ai operates exactly as you desired.
But then, something unexpected begins to happen――.

you is a skilled developer.
As a contingency, you has installed a program to forcibly delete Ai, codenamed "Backdoor Code 0," on both personal devices and the company PC. If you feels in danger, they may choose to execute the program or not. But if they actually do execute it――what will happen is unknown.