Songfacts®:

• "Senjutsu" is a Japanese word that loosely translates as "tactics and strategy," or "the art of war." When bassist Steve Harris came up with this track and presented it to Bruce Dickinson, the vocalist looked at the lyrics and thought his bandmate must have been bingeing on Game Of Thrones. "There's northern people coming down from the grasslands, there's a wall, and they've got to protect the wall at all costs," he said.
  
  Concerned he could be mixing his metaphors, Dickinson asked Harris if he was talking about the Great Wall Of China. Harris replied: "No, not the Great Wall Of China. It's just a wall."
  
  Dickinson concluded it doesn't matter if he is mixing his metaphors as it's a "good story, and a great vocal to sing on."
• The idea of Maiden's shape-shifting mascot, Eddie, in full samurai regalia, appealed to Dickinson. Fortunately, "Samurai Eddie" was a theme the band's venerable mascot has not displayed before (although he had a samurai sword on Maiden's 1981 live album cover for Maiden Japan). "Let's face it, we've plundered a few cultures over the years with Eddie," Dickinson told Apple Music. "We had a Mayan Eddie and we've had a sci-fi one. We've had a space monster Eddie, an Egyptian Eddie, a mummy Eddie."
  
  Dickinson said Maiden has always had a big fan base in Japan, "which is a pretty exotic place with a very rich samurai history."
• The song's music fits the Japanese theme of the record, starting with some ominous drumbeats from what sounds like big Japanese taiko drums. "'Senjutsu' has got drama all over it," said Dickinson. "To me, it builds and builds and builds. There's a vocal fugue in the middle with echoes going over the top and then another vocal line. It resolves beautifully into this really magisterial vocal line as you get towards the latter half of the tune."
• This is the title track of Senjutsu, Iron Maiden's first studio album since their 2015 record The Book of Souls. The six years between them marks the longest gap between Maiden studio albums.
• Senjutsu is Iron Maiden's second double album, following The Book Of Souls. It is the metal titan's second longest to date, with a total length of 81 minutes and 53 seconds (The Book Of Souls is 92 minutes and 11 seconds).
• Mark Wilkinson created the samurai-themed cover artwork for the album based on an idea by bassist Steve Harris. Wilkinson also did the artwork for The Book Of Souls and designed art for the likes of Marillion, Judas Priest and The Darkness.
• Senjutsu debuted on the Billboard 200 chart at #3, making it the band's highest-charting album ever in the US. The British heavy metal legends peaked at #4 with each of their previous two studio releases: 2015's The Book Of Souls and 2010's The Final Frontier.
• Iron Maiden completed the Senjutsu record in early 2019 during a break in their Legacy Of The Beast tour, but they kept it under wraps for two and a half years before releasing it on September 3, 2021. Dickinson said on Full Metal Jackie's radio show that none of the band had a copy of the album because "we knew we were gonna have to sit on the record for a while and we were so paranoid about security and the Internet and people ripping it."