Mr. Passion is a boss in Mother 3. He is found during Chapter 2 during Duster's infiltration of Osohe Castle. When found, he is in the middle of conducting and levitating several objects, including a mouse. Mr. Passion is furious when Duster refuses to listen to his song, calling him an 'artistic know-nothing", and attacks him. Upon his defeat, Duster can enter the next room and retrieve the Noble Spitoon. The mouse will also inform him of a couch he can sleep on to heal.
He reappears later in the game as Lord Passion, wearing a red suit and a new hairstyle, and resumes conducting music, this time levitating the Mystical Shoes, an excellent weapon for Duster. After he is defeated again, the Mystical Shoes can be picked up. However, he can only be encountered during Chapter 5. Once Chapter 5 is over, even if the player returns to Osohe Castle, the party does not have the Rope Snake and so cannot cross over the gaps in the floor in order to eventually reach him.
Mr. Passion can throw candles, make a chair charge, brandish his baton, and even throw the mouse at Duster. There is also a chance that he could get lost in the music. After taking half the maximum HP of damage, he becomes more exuberant, raising his attack power and changing his behaviour. Because of this, he will then occasionally send everything but the kitchen sink flying, which is capable of causing major damage. His battle music is Family Matters: 2nd Movement.
True to his name, Mr. Passion has a crippling weakness to crying; Duster's Smoke Bombs can easily render most of his attacks a non-issue.
As Lord Passion, he uses the same move-set, but he is more powerful, and can now inflict several status changes by playing melodies that can numb or put characters to sleep. Additionally, rather than throwing the mouse, he throws one of the Mystical Shoes. However, it still is by far his weakest attack. His battle music in this form is Ode to Ancestors: 8th Movement. He is still weak to crying, and has an additional weakness to Fire.
Both forms of this boss have battle sound as its Battle Sound 28 which falls under Code Numbers 520 for regular attack, 521 for Smaaaash! and 552 for Miss.
His theme is the Beethoven's Symphony No. 5.