Note: Batman and K-On! are not owned and created by me. This story is dedicated to Bill Finger, Adam West, and all of the wonderful people who have helped the Batman franchise.
Batman was trying to find the Joker, but the Joker was in a city that Batman had never been to before so finding him was a challenge. Batman said "The Joker Detector on my utility belt is reporting to me that the Joker is nearby." Batman looked around and saw a band area. He said "Oh my. The Joker could cause trouble to the singers. I need to find the Joker faster than ever."
Meanwhile Yui, Ritsu, Mio, Tsumugi, and Azusa were having band practice. As usual Mio and Azusa did most of the practice while the other three goofed around. Mio politely said said "You shouldn't be ignoring practice today. Our next concert is tonight."
Ritsu replied "Whatever. We're all prepared. You're the one who needs to practice on not being so shy."
Mio nervously said "Singing in front of so many people can be scary at times. The fact that you forced me to be the lead singer hurts my confidence as well."
Azusa replied "You're the best Mio. No need to worry."
Yui said "Well there are several things to worry about, but I doubt you want to know that."
Tsumugi replied "Sounds exciting to me."
The Joker entered the band room and said "Greetings fools."
Yui responded "We're singers, not fools."
The Joker said "I have to make sure my crimes with Batman stay fresh. That's why I've come to this overrated high school. This caper of mine is really confusing Batman. I love messing up his brain." The Joker did a evil laugh.
Mio nervously asked "Are you going to do anything scary to us Mr. Joker?"
The Joker said "You don't need to be scared. My intention is to mess around with Batman, not to cause any trouble here." The Joker and Yui started playing catch with a microphone. The Joker accidentally threw the microphone out the window and did a evil laugh.
Batman looked around the band area and saw a immature looking janitor who was spilling bottles of soda on the floor. Batman asked "Have you seen the Joker?"
The janitor asked "How does the Joker look?"
Batman was surprised that the janitor didn't know what the Joker looked like. He said "The Joker has clown makeup on his face and he usually wears purple costumes."
The janitor replied "Sounds like he would fit in with a majority of the singers here."
Batman said "Singers may dress eccentric sometimes, but comparing them to the most dangerous criminal in the world is disrespectful."
The janitor replied "I'm sorry about that Batman." Batman kept looking around for the Joker.
Meanwhile the Joker was playing around the band practice room. The Joker started playing the drums and said "I was nominated for best drummer at Arkham Asylum's annual concert event, but I lost to the Penguin." The Joker accidentally broke the drums.
Mio said "Ritsu needs those drums for tonight's concert."
The Joker replied "Calm down Mio-chan. She can use the broken drums tonight. I think that playing broken drums instead of the typical quality of drums will make tonight's concert much more entertaining." The Joker did a evil laugh.
Yui asked "Do you have any guitar practice?"
The Joker said "I'm the master at playing guitar." The Joker grabbed Yui's guitar and started playing it. He was surprised by how well made the guitar was and how nice it sounded. However the Joker thought that high quality items aren't amusing so he destroyed the guitar.
Yui said "I loved that guitar. It was like a friend to me."
The Joker replied "How amusingly pathetic." The Joker did a evil laugh.
Mio said "Mr. Joker you've been really rude to my friends."
The Joker sarcastically replied "I'm deeply sorry about that. I love music bands that I tried really hard to fit in. I really sorry for being a troublemaker."
Azusa said "We need to get the Joker out of the band practice room."
Mio replied "We can't kick him out."
Tsumugi said "I think that I know how to calm the Joker down." Tsumugi handed the Joker a cup of tea.
The Joker pretended to be honored to get a free cup of tea. He jokingly shook Tsumugi's hand to thank her. He said "This tea looks really great. However I think that this cup isn't where it should be. In fact I know the perfect place to put it." The Joker tried to throw the tea in Tsumugi's face, but Mio knocked the tea cup to the ground. Mio was scared that the Joker would get mad at her. The Joker had a annoyed expression on his face.
Batman entered the band practice room and found the Joker. Batman said "Trying to ruin a concert is pretty evil even by your standards Joker."
The Joker replied "But I have to make sure my crimes don't get boring for either of us Batman. I always want to keep things exciting."
Batman said "I admire your desire to make life special, but your plans to achieve that are immoral antics that I don't like."
The Joker grabbed the broken guitar and tried to throw it at Batman, but Mio caught it before Batman got hurt. The Joker angrily said "Your heroic acts are quite annoying."
Mio nervously replied "People have to do what's right."
The Joker angrily said "I don't do what's right." The Joker calmed down and said "I do what's left."
Batman said "I hope that you at least have the decency to surrender Joker."
The Joker replied "I never give up Batman."
Batman said "Not giving up is usually a admirable thing to do, but you should give up."
The Joker looked around and said "This band room lacks an important part of music: dancing. Lets dance together Batman."
Batman replied "The only criminals that I would ever dance with are Catwoman and Talia al Ghul."
Yui said "You would probably also dance with Poison Ivy and Harley Quinn."
The Joker grabbed one of the broken drums and tried to throw it at Batman. The Joker said "I hope that I hurt Batman." He did a evil laugh.
Batman replied "The drum didn't land on anybody which means you failed to win another drumming contest Joker."
The Joker grabbed Yui and Tsumugi, but it was too hard for him to carry two people so he tripped and landed on the floor. The Joker said "You girls have so many pounds of niceness that my evil strength didn't work."
Batman helped Yui and Tsumugi stand up and asked "Are you two ladies okay?"
Yui said "Of course we are Batman."
Tsumugi replied "This is the fourteenth time we've fallen this week."
Batman said "There's some important safety lessons you should learn about."
The Joker started staring at the window. He said "I got a great plan."
Mio asked "What are you going to do Mr. Joker?"
The Joker said "There's some soft stuff outside that'll help me with my plan. I'll throw you and your friends outside. After you and your buddies gently fall down I'll lock the door so you won't have any music equipment for tonight's concert. This'll be my most evil act of the month." The Joker did a evil laugh.
Mio was scared about the Joker's plan. Instead of just being worried she decided to try to save her friends. Before the Joker tried anything Mio gently punched the Joker. The Joker fell outside on some soft stuff.
Batman walked outside and grabbed the Joker. Batman said "Your concert will be in prison instead of onstage Joker."
The Joker sighed and replied "Buy me a new guitar at the store Batman. I'll show the Penguin that I'm the master of evil guitar playing." The Joker did a evil laugh.
Batman said "Thank you for your help Mio. You helped stop the Joker more than I did today."
Mio replied "You're always the real hero Mr. Batman."
Azusa said "Since the Joker broke our music equipment we can't play at the concert tonight." The Joker giggled.
Batman replied "Thankfully the Joker didn't break the microphone. You can sing."
Ritsu said "Since you're the lead singer Mio you'll be in charge of things tonight."
Mio replied "But I'm still really nervous."
Batman said "I think that a concert is much less of a challenge than defeating the Joker. I believe that you'll do a great job."
Mio replied "Thank you Mr. Batman."
Batman waved goodbye to the band and took the Joker to a nearby prison.
A few hours later the concert started. Batman was in the crowd. Mio was still nervous, but she started singing. The crowd really liked her song and her voice. After the song was over most of the people clapped.
After the concert ended Mio said "Thank you for giving me the confidence that I needed Batman."
Batman replied "You were the hero today, not me. Sometimes just being a kindhearted and brave person is enough to be a hero."