Erika to Satoru no Yume Bouken/en

Erika to Satoru no Yume Bouken (えりかとさとるの夢冒険, "Erika and Satoru's Dream Adventure" ) is a Famicom game developed by Atlus for Namco.

Hidden Music
Track #24 in the .nsf is a slightly remixed version of the first stage of The Karate Kid. Both games were composed by Hirohiko Takayama. Even though the song doesn't play during the main game, it does play during the hidden message.

Hidden Messages
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Programmer "Hidemushi" left a vulgar message for his co-workers which is accessible after waiting an hour and a half at the ending screen and pressing a combination of buttons on both controllers.

Accessing

 * 1) Beat the game. The last screen on the ending is a photo of the characters with the word おしまい (END).
 * 2) Let the screen sit for 18 minutes. The photo goes black-and-white.
 * 3) Let the screen sit for 18 more minutes. The photo goes sepia-tone.
 * 4) Wait 55 minutes. The music stops suddenly.
 * 5) After the BGM stops, press A + B + Start + Select + Left on controller 1, and A + B + Right on controller 2. New music starts.
 * 6) Press B + Select + Right on controller 1, and B + Right + Down on controller 2. Hidemushi's message will start.
 * 7) Once Hidemushi's message stops, press A + B + Up on controller 1 for his last message.
 * 8) Wait 18 more minutes, and the game goes back to the title screen.

Translation
"'Mmm, that's a nostalgic song playing. Those were good times. Meanwhile, who the hell are these people with this project? I'm so glad it's over. You think it's nothing but good memories? Hell no! Let's use this space to give out some thanks."

"First off, Kaoru Ogura, who ran off with some guy in the middle of the project. Yes, you, you bastard. Don't show up at the office without showering after having sex 6 times the previous night. Next, Tatsuya Ōhashi. Yes, you, you bastard. Don't give me your flippant shit — coming in late on the day we ship the ROM like nothing's amiss. You can give me all the porn you want; I'm not forgetting that one. All that fucking weight you put on. No wonder you paid out 18,000 yen and still got nothing but a kiss out of it. Kenji Takano, Namco debugger. You are a part-timer; don't dick around with the project planner. And finally, Kiyoharu Gotō, the biggest thorn to my side in this project. Yes, you, you bastard. Once I get a time machine, I’m sending you back to the Edo period. Go do your riddles over there."

"Ahh, that's a load off...wait, no it's not. Kiyoharu Gotō — yes, you, you bastard. Aaaagh, just disappear already."

"Come to think of it, some people were helpful to me, too. Mr. Okada, who took all the good stuff. I know all about your abnormal tendencies. Yamagishi, who swore off soaplands until the project was over. Go ahead, knock yourself out now. Iwata, who joined in midway and gave it all he had. Sorry I yelled at you. Keep hanging in there. Fujimura, Udopyu, you probably had it the worst of all. Thanks. I mean it. Gotō's the one to hate here. Also, Takayama, Kudō, Suzuki, Makki, Kaneko, Aihara, Sato (the angel of my heart), Iga. Thanks, everyone."

"Yoko-G, good work. This game is dedicated to your wife's birthday.'"

After doing step 7:

"'Kazumushi, I'm sorry I couldn't come back home much. I love you and always have. Hidemushi'"

Other Messages
The last characters of the first two 5 character segments and the third character from the third segment used as passwords throughout the game spell out a message:

＜一人用＞

1章：かきかか い 　かかかか い 　かか か みあ　ひそそささ

2章：かけかか み 　かかかか て 　かこ ろ みあ　ひつたちけ

3章：かちかき き 　かかせか さ 　かさ ま みあ　ひちたそす

4章：きちかけ い 　かこそか ま 　かさ に みあ　ひてきそと

5章：ちちかけ こ 　かこそか ろ 　かさ す みあ　ひとなつく

＜二人用＞

1章：かきかか や 　かかかか め 　かか た みあ　ひてちたす

2章：かけかか こ 　かかかか ん 　かこ な みあ　ひつなたす

3章：かちかき や 　かかせか つ 　かさ ら みあ　ひてとつそ

4章：きちかけ は 　かこそか や 　かさ く みあ　ひととちち

5章：ちちかけ う 　かこそか せ 　かさ ろ みあ　ひつちちし

いいか　みてろ　きさま　いまに　ころす やめた　こんな　やつら　はやく　うせろ Right then! Just you wait! I'll kill you right now! I changed my mind. Hurry up and get out of here!

Other messages are accessible within the game by entering specific passwords.