What's this episode 1?
Normally included in a separate disc with Tron ni Kobun (the disc on the right) (http://www.rockmanpm.com/i/rockmancollection/ps_tronnikobun.jpg), it's "kinda" like a demo disc of Rockman DASH 2, but still not. It's like a very small prequel to the second game, but it was only available in Japan. You get to play 4 different missions that you can select from a starting menu with funny images as the mugshots.
(http://www.rockmanpm.com/i/dash/rockmandash2/episode1/game1b.png) (http://www.rockmanpm.com/i/dash/rockmandash2/episode1/game2b.png) (http://www.rockmanpm.com/i/dash/rockmandash2/episode1/game3b.png) (http://www.rockmanpm.com/i/dash/rockmandash2/episode1/game4b.png)
The first one is a training mode where you get to learn how the controls for the game works, as well as talking to a few of your friends on this town (that didn't make it to the final version of the game) and enter a dungeon to learn the controls there as well. The second mission requires you to look for pigs hiding across the grassy plains of Calbania, grab them with your Claw Arm and give them to Sue. The third one is more dungeon/ruin exploring, with plenty of Reaverbots to fight.
The last one is a Legends fan favorite. Tron Bonne decides to mess around with Rock and offers him to join the pirates. Rock think about it, and a day dream shows "what if Rock and Tron joined forces". A cute cutscene that is so laughable, Rock shoots people and stuff and they scream in terror. Rock wakes up from the day dream and says No to the offer. Tron failed to lure him so they kidnapped Roll and now you have to run through plenty of the Bonne family's machines and Servbots, who are protecting keys to reach Roll. In a last fight with Tron herself, you see the wooden box that Roll is in is empty. Someone else already rescued her, but who would that be? ;3
It's a very funny little "demo disc", and if you ever find it, I suggest you try it out, or look at some youtube videos. ^^