@meidunk The bottle of tea with milk. Remember the tour on publishing house? Remember they were alone in the subway? In my opinion it was on that tour that Ichikawa conquers Yamada, specifically in the elevator scene
For those of you who do not know what that bottle was actually. It was actually the one she gave to him to drink after he got back from Akita. He was going to her house to drop the manga off but she walked to his house and they ended up meeting in front of his house. That's the bottle she opened for him and gave to him to drink when they went to go sit down at the park. She gave him the scarf and sat down to hold his hand. She kept it and I just realized what it was !