Although not much is known about this Chapter, it is known to be the first, 4 levels, 3-Regular and a Boss added on.
The levels are listed below, along with their subtitles. Every level has a hidden scroll, called Sunken Scrolls, and if you find them, you get a page with some information on it. Boss level scrolls however, are given to you after you defeat them. Inside of boss scrolls contains a weapon blueprint which you can give to Sheldon and he can sell it to you. The weapon for Boss 1 is the Custom Splattershot Jr.
The Octotrooper Hideout
~Catch that Zapfish~
Sunken Scroll: When you reach the area with 5 octopuses that attack you, there are pillars. Use the middle one to climb to the highest to get the scroll
Lair of the Octoballs
~Splat Your Way to the Top~
Sunken Scroll: Near the middle of the level, there will be a mesh catwalk. Look down and you will see a crate. Turn to a squid and break the crate to get the scroll.
Rise of the Octocopters
~Leap to Victory~
Sunken Scroll: Proceed to the part with 2 pillars. Climb the short one then jump from that one to the tall one. On top of the pillar there should be a crate with the sunken scroll.
~First Boss Fight~
Sunken Scroll: After you defeat Octostomp, there should be the Zapfish, scroll and the single player currency. The scroll is for Custom Splattershot Jr. which you can take to Sheldon and you can buy it from him.