Are you sure about that? Because I have tested it again and while you indeed can meet Shiba again, the dialogues is different. If you never help him, the producer introduces you to him instead.
Very certain. i was ACTIVELY searching for him and i didn't see him, while the producer DID introduce him, shiba still had the same dialogue. perhaps it was a fluke,
He's in shopping mall the first time you go there. And is always there until 16th January. If you go to shopping mall (before 16th January) and don't find the scene in shopping mall, that means you already get the scene.
I have checked the code multiple times, and the thing you mentioned shouldn't happen.
Wierd I'll play through it again. I did get off a long shift at work, maybe i just blanked out. I appologse for the stress i likely put on you. =D keep up the hard work.
edit: just preordered the arrtbook edition. =D