Three First Discoverers (三人の第一発見者 San'nin no Daiichihakkensha) is the 792nd and 793rd episode of the Detective Conan. In this episode, the first and second hints about Rum are introduced.
 Part 1
After the detective boys have played soccer, Conan asks Haibara about Rum. She reveals that she never met him, but she has hear three different descriptions of him. He should either be a strong man, a feminine-looking man or a old man. She also recalls that he had a characteristic, that everyone in the organization agreed on, but she can't remember what. Ayumi suddenly sees an young boy standing and staring at an apartment. She remembered that he had also been standing there earliere that day. When the children asks him, the boy breaks down crying. He tells them that a woman who lives in the apartment had asks him to keep an eye on her door. She was going to have three visitors, and if she didn't come out after the last one had left, then she had been murdered, and the boy should call the police. The detective boys decide to check out the apartment, and on their way, the boy tells them, that he barely knows the lady. After the death of his parents he moved in with his uncle and lost contact with his old friends. The lady would sometimes come and play with him on the playground, when he was lonely.
|| Yasue Komai's apartment
|| Yasue Komai
| Cause of death:
|| Ronpei Sakaba, Kuramichi Habanaka, and Denji Shibakaru
 Part 2
- Lum Invader, a character from the external manga series Urusei Yatsura by Rumiko Takahashi, is a pun on the similar sounding of the names "Lum" and "Rum" due to the Japanese pronounciation of the Katakana syllable "ラ" ("ra") used in both. In the Japanese original, Haibara adds the word "-datcha", which is a famous speech affection used by Lum.
- Incidentally, Fumi Hirano, Lum's voice actress in the manga's animated conversion, previously performed the role of Reiko Shimizu in the Detective Conan movie The Private Eyes' Requiem.
- ^ In the closing song, Mamoru's name was indicated as Boy.
 See also