4℃ is incredibly skinny, to the point of almost being anorexic.
Similarly to Okabe his persona makes him appear delusional but the difference is 4℃ is actually delusional. 4℃ acts like a Chuunibyou believing himself to be powerful and cunning. 4℃ is angered easily, for example when he reacts aggressively to Okabe bumping into him in the My Darling's embrace game. He tends to act smug around others as well as treat them as inferior to himself unless it benefits him. Furthermore, 4℃ is extremely selfish and always seems to react in an unfeeling and uncaring way towards others.
In Steins:Gate My Darling's embrace, 4℃ is briefly encountered in the prologue warning Okabe to not enter Faris' cafe claiming it sucks and is a waste of time and money. Later in the game in one of the routes, the timeline greatly differs as 4℃ is infamous among the maid cafe world for using skeevy strategies and scare tactics to monopolise maid cafes around Akihabara.
Though 4℃ prides himself on being called 4℃, pronounced "Shido", Okabe prefers to belittle him by calling him "Yondo". "Yon" being an alternate reading for the number 4 in Japanese.