@DanganronpaRein I don't think SaiGoku is at all that well known ship in the fandom. I myself started to ship them from the love hotel event
Shuichi x Joker was a ship I randomly thought of XD plus Shuichi is a detective who seeks out the truth, (DRV3's main theme is Truth vs Lies). Joker is a phantom thief who through his shadow, unleashes his suppressed self and "breaking the chains" (Persona 5's main theme is freedom). So you could say, both characters fight for justice.