You Lied To Me (A Detective Conan/Case Close...
Conan has only two goals: To protect his relatives and friends, and to try to stop the Black Organization.
Conan knew that the Black Organization is still out there, trying to find Ai and him to... kill them. Conan tries to stop the Organization from doing so, but each time he tries to stop them, this leads to his friends and relatives knowing his so long hidden secret one by one. Conan said that they need to keep this as secret and secret only, and that they shouldn't tell anyone, especially Ran.
But when Ran discovered the truth, she couldn't help but wonder:
Why was Conan lying to her all this time?