Wow, someone else who knows Makoto Kobabyashi! Great!
Well, you may be right, it's a kind of style reminiscent of Kobayashi for sure. That vaguely realistic, although highly comical style (if that makes even sense, lol...). Could it be that Yamada Koichi was an assistant of Kobayashi? But they have about the same age...maybe they were assistants of another mangaka together? who knows...