I Became the Demon King’s Right Hand so I Will Alter the Original Story

I Became the Demon King’s Right Hand so I Will Alter the Original Story, Maou no Migiude ni Nattanode Gensaku Kaiaku Shimasu / 魔王の右腕になったので原作改悪します
Office Lady falls from a building is reincarnated into another world and ends up at the Devil Kings castle. Can she save him from the bad ending?