Diner chapter = character building and lore.
Kaoru 薫 is a gender-neutral name which means "pleasant fragrance", a farcry from numakawa's guess of Kanji 寛治 (lenient/gentle+governance).
Numakawa is Takuya, 拓 meaning clear (the land), open, break up (land). / 也 meaning to be (classical).
Isawa is portrayed as the muscle of the group in Kaiji, but in the Foreman manga he's the comic relief/zoomer of the group which is great. When I watched Tonegawa back in 2018, I was a bit annoyed they messed with the canon by retconning some of the characters but now I like these fleshed-out versions better.
Title: 実無, contraction of 実の無い which refers to their conversations.