Ep. 400: Ran discovers the four-digit lock code on Conan's phone and confronts him about his secret.

400

Ran finds a four-digit lock on Conan's cellphone and recalls Shinichi using Hiragana and numbers from license plates to form words. In the past, Shinichi reported a car with an illegal plate, noting that the characters "shi" and "he" are prohibited, which helped police stop criminals before a bank robbery. Returning to the present, Ran unlocks the phone using the number sequence for "Sherlock," which is 4869. Suspecting Conan deleted her messages, she resents the situation until receiving an irritated call from Shinichi. Conan appears, retrieves his phone, and returns to his room, revealing he used a prerecorded message to protect his secret. He then gives Ran his phone number, accepting the associated dangers.