Conan discovers a photo on a Mizunashi Rena fan page, that just happens to have a woman in the background that resembles Mizunashi Rena and who is carrying a bag of groceries, and also has Tsutenkaku in the background. So he thinks that there is a possibility that she might have used to live in Osaka, and so he requests Heiji's assistance. He asks him to have inspector Otaki to secretly check to see if any woman with the name Mizunashi or Hondo ever lived in Osaka and who might have gone missing at some point. That is because Conan thinks the Hondo appears to be searching for his sister or the enemy of his sister, in other words he believes that someone with the black organization murdered Eisuke's sister and is now posing as her after having plastic surgery. That would connect Eisuke's motives for looking for her, and the reason that Gin talked about Rena murdering some man named Hondo(someone also related to Eisuke and "Rena" that she had to kill when taking over "Rena's" identity ).
Inspector Otaki checks the school records in Osaka for the last 20 years but no one by the name Mizunashi Rena shows up. Also there were discovered to be two people around Tsutenkaku who had a picture from about 10 years ago that had a woman in them that looked like Mizunashi Rena (The picture Conan saw on the fan site) but it doesn't appear that there was anyone that knew her at that time. But there was a restaurant owner in Osaka that did know Hondo Eisuke. He would go to the restaurant with his dad. His dad was a quiet person and was call Hondo. (So, it appears to maybe be the person killed by "Rena" that Gin was talking about) His dad would sometimes go there with his colleagues from work but a few years ago he suddenly stopped showing up. The shop owner and Eisuke's dad got along well and would sometimes sit and talk even after the shop closed, but the 80 year old shop owner passed away from cancer so they (Conan and Heiji) don't know what those two (Dad and owner) talked about. But, the among colleagues that he met with where some foreigners. Also, he (Eisuke's dad) and the others were dressed in dark or black clothes, seeming like they might have come from the black orginization.
The shop owner also had a grandchild who went to college in Osaka and now runs a model shop in Tokyo, and Conan is going to try to get some information from him, but he also met Hondo when he was in Osaka so he might be under surveillance from the black orginization.
They find out a few things from the grandchild. One thing being that the man, while he was with 3 or 4 foreigners dressed in black, was heard saying "いよいよ潜る" which means "to dive deeper and deeper". The grandchild thought he was talking about scuba diving. Also, the foreigners said "Good luck" and "No pain, no gain".
They found out that the mans child was never there when he was with his business partners.
And that the man was hired by "The Company".
They got this picture which is apparently him and his son.
