In which episode of Detective Conan did Conan meet Sera for the first time?

Conan met Sera for the first time in episode 646 (Mystery Duel in the Ghost Hotel)

Plot summary: At the invitation of Yuanzi, Conan and Xiaolan went to Cup with her. They were enjoying "all you can eat cake" at a hotel in Japan. However, on the way to the bus, they met a Jeet Kune Do master and got in the car together. In the car, she introduced herself. She turned out to be Masumi Sera and called herself A female high school detective, the sister of FBI investigator Shuichi Akai and shogi player Hideyoshi Haneda.

After some pleasantries, the three of them arrived at the Cupido Hotel. Xiaolan and Sonoko were disappointed to learn that the all-you-can-eat cake restaurant had closed. At this time, there was a sudden scream, and there was a The man fell from a height and died. Witness Hirukawa said that a figure flashed across the roof, but when Conan rushed to the roof, he only found his coat and shoes.

Extended information:

Follow-up——

The police, Conan and the detective Sera who met on the bus entered the annex to investigate. They were on the second floor An electric wheelchair with fishing line was found, paint and oil drums were found under the window on the sixth floor where the deceased fell, and the annex used an elevator with a door at the front and rear. After connecting all these clues, Conan discovered That's the murderer!

Sera solved the case one step ahead of Conan and re-created the scene. However, the result was not what everyone expected. The doll did not fall. What went wrong? Although the reasoning process was wrong, she seemed to be Make mistakes on purpose to see how Conan reacts. Sera also showed internally that she understood Shinichi's situation.

Conan was impressed by the fangs exposed when she smiled, so he felt that he had seen Sera before or someone who looked like her. Xiaolan also feels familiar with Serang.