About halfway through Shōgun Episode 6 “Ladies of the Willow World,” Toranaga (Hiroyuki Sanada) is sitting with his innermost circle and his most trusted general, Hiromatsu (Tokuma Nishioka) declares it is time for “Crimson Sky.” Half the group looks at Toranaga in nervous expectation, while the other half is utterly befuddled. Yabushige (Tadanobu Asano) potentially speaks for most of FX‘s audience when he asks, “What is Crimson Sky?”

**Spoilers for Shōgun Episode 6 “Ladies of the Willow World,” now streaming on Hulu**

Even though Hiromatsu goes on to bluntly describe Crimson Sky as a battle plan to make one violent push towards Osaka, where they will conquer Toranaga’s enemies and install the beloved and brilliant daimyo as Shōgun, it’s more complicated than that. Indeed, as Yabushige’s clever nephew Omi (Hiroto Kanai) points out it’s a dumb plan that amounts to suicide. After the earthquake, Toranaga doesn’t have the numbers to take the heavily fortified Osaka. Furthermore, with zero friends left on the council of regents, there’s no obvious (or secret) alliance to depend upon. There’s chatter that Toranaga’s half-brother Saeki Nobutatsu could help a bro out, but would that be enough?

Well, by the end of Shōgun Episode 6 “Ladies of the Willow World,” Toranaga decides there is no other choice. After all, the latest installment of the FX hit ends with Toranaga’s nemesis Ishido (Takehiro Hira) violently massacring the hitherto rather neutral (and under the radar) regent Sugiyama (Toshi Toda) and his entire family. (The idea sort of comes from Fumi Nikaido’s terrifying Ochiba no Kata, who advises the low-born bureaucrat to force fate’s eye upon him to scratch it out. A poetic way of saying to get your hands dirty.)

So this week’s episode of Shōgun ends with Toranaga officially declaring Crimson Sky. So what does that mean? What might you be potentially missing? And what has to work for his plan to succeed? Here’s everything you need to know about Crimson Sky…

Shogun: What is Crimson Sky?

Crimson Sky is the code word used to describe a top secret plan to engage in total war with Toranaga’s adversaries. It means there’s no more room for debate, strategy, or politics. Toranaga is going to assemble all of his available forces and hit Osaka in one furious blow. When his enemies are defeated, he will take up the mantle of Shōgun, the title given to an all-powerful warlord in Japan who happens to come from one of three noble bloodlines. (If you take over Japan and are not of royal blood…you are a Taiko.)

As it’s pointed out, in the FX version of Shōgun, this is a last gasp effort at survival. Politically, Toranaga is now cooked, as Ochiba and Ishido are murdering anyone who does not submit to their authority. Furthermore, he has lost his troops. His one hope lies in convincing his half-brother Saeki Nobutatsu (or Lord Zataki in the book) to join his cause, offer his armies, and cover his rear so Edo isn’t attacked while his forces are on the march to Osaka.

That’s what Crimson Sky is in the FX version of Shōgun. Crimson Sky is a tiny bit more complicated in James Clavell’s original novel of the same name.

The concept of Crimson Sky is introduced fairly early in the book within a passage that reveals that Toranaga keeps a top secret code that only he, his long-time favorite and most trusted consort Kiri no Kata (Yoriko Dōguchi), eldest sun Noburu, and second son and named heir Sudara know*. The book version of Crimson Sky is a bit more sophisticated than just a plan to charge Osaka. We read that Toranaga has not only embedded loyalists all over Japan to spark insurrections in various territories, but he’s carefully laid out plans to attack various targets. If Toranaga is killed by his enemies, Crimson Sky is immediately instigated by his surviving inner circle.

The long and short of it is Crimson Sky means Toranaga is hurling everything he has at his enemies. It means there’s no going back and that blood will soon be shed.

*If you’re only watching the FX show, you don’t have to worry about Noburu. He’s Toranaga’s oldest and most intelligent son, but because of a physical ailment, he’s deemed unworthy to be his father’s successor (to Toranaga’s regret). Sudara, however, might pop up in a future episode because he’s the son married to Ochiba’s sister — whom you’ll remember was having a baby in Edo in the early episodes of the show. You also met Kiri all the way back at the beginning of the series. Toranaga pretended to be her to escape Osaka. She is still there with his newest consort, who was pregnant when the main cast left. Note that Nagakado, (Yuki Kura), Toranaga’s whiny son who follows him around is NOT in the top secret Crimson Sky group chat in Clavell’s version.