Ryudamon

Q:If I place 1 [Shuu Yulin] from my hand as this Digimon's bottom digivolution card at the start of my main phase, does this card's effect prevent it from being affected by the [Security] effects of my opponent's Security Digimon?

A:Yes, it isn't affected. [Security] effects on Security Digimon are treated as Digimon effects, so the "this Digimon isn't affected by the effects of your opponent's Digimon" effect prevents such effects from affecting this Digimon.