Iji 1.7 - Official game guide|
Introduction - Sector 1 - Sector 2 - Sector 3 - Sector 4 - Sector 5 - Sector 6
Sector 7 - Sector 8 - Sector 9 - Sector X - Sector Y - Sector Z - Misc secrets
Unlockables - Weapons - Items - Enemies - Bosses - Trivia - Text dump
The game doesn't do a very good job of pretending that this is the final Sector, especially since you can establish a truce and walk right through it.
Inside the first ventilation shaft, just keep going right and drop down to the ribbon.
Get Strength level 4 or higher, 6 is recommended. Go to the very last Tasen Soldier in the level (A) and kick her down to the left. Alternatively you can use an Impulse launcher to do the same (passive Tasen level 6). Go left and stand underneath the window, and wait for the Soldier to fire a rocket. Jump into the rocket in mid-air to be sent flying through the window to the left. The poster is outside.
In the Komato camp (B), use the Hyper pulse (Resonance detonator + Pulse cannon + Crack 6) on the shield door to the upper right.
Secrets + notable modifiers
Kill ten or less enemies before this Sector, and a Tasen Soldier called Vateilika will meet up with you and form a temporary truce. Krotera won't like it, and it won't last past Sector 3 no matter what you do. The truce removes a lot of enemies and doors from the Sector. As long as you don't kill Vateilika after the truce is formed, she'll show up again in Sector 7. She'll also appear in Sector 9 if she killed Krotera and you're still pacifist by then. Note that firing your gun, attacking the Tasen or breaking Shield doors where any Tasen can hear it will break the truce.
Vateilika kills Krotera / Krotera is a jerk
If you established the truce and it's still intact when you get to Krotera (don't anger any Tasen), Vateilika will appear in the boss room and shoot Krotera before the fight begins. This lets Iji avoid having to kill Krotera herself.
The Soldier guarding the final lift to Krotera's room (A) looks like anyone else, but she is NI010:GOST Maeja, the girlfriend of the diary-writing Tasen KG111:PAIE Wak Torma. Don't kill her, and both of them will survive Iosa's attack on the Tasen base in Sector 9, no matter what else happens. Note: KG111:PAIE's diaries appear in Sectors 3, 5, 7 and 9.
Take the left path when falling down the first vertical ventilation shaft, and you'll eventually see two doors (C): a Shield door that requires a Strength of 10, and behind it a Security door that requires a Crack of 10. To open them both, you need to do a Nanofield reboot (see Misc secrets) after opening the first one and redistribute your points into Crack. Inside are logs on how to reach various posters. You can actually enter this room on Normal difficulty without Nanofield rebooting, but this requires you to obtain the Supercharges from Sector 1 and 2, get the Supercharge in Sector 3, and then die and revive at the Checkpoint. This gives you enough points for level 10 Strength and Crack at the same time.
Do not read any of the Komato logbooks in their camp (B) and the following chat with Dan will change to reflect this.
Early Pulse cannon
With a Crack of 2 or higher, simply crack the door in the Komato camp (B) to find the game's first Pulse cannon.
Jet Force Gemini
A logbook about lifts near the start of the Sector references a song from the alien disco in JFG.
The Legend of Zelda: Link's Awakening
As the most obscure of all references, there is a place just to the left of the ammo storage with blits and a single Commander where the background tiles form a certain pattern. This pattern is the same as the one the sand tiles form among the rocks at the entrance to Turtle Rock in Link's Awakening.