Trivia

The Franxx pilots' names are all designated after Japanese words for numbers:

• Hiro is designated 16 ("hi"-"ro", 1-6)
• Ichigo is designated 15 ("ichi"-"go", 1-5)
• Goro is designated 56 ("go"-"ro", 5-6)
• Miku is designated 39 ("mi"-"ku", 3-9)
• Kokoro is designated 556 ("ko"-"ko"-"ro", 5-5-6)
• Futoshi is designated 214 ("fu"-"to"-"shi", 2-10-4)
• Mitsuru is designated 326 ("mi"-"tsu"-"ru", 3-2-6)
• Naomi is designated 703 ("na"-"O"-"mi", 7-0-3)
• Ikuno is designated 196 ("i"-"ku"-"no", 1-9-6 - it's actually a Japanese pun as "ku" is turned around to read "no", just as 9 is turned around to read 6).

Zorome, who is designated 666, stands out as his name is Japanese for "repdigit", a number that is the same (11, 22, 33 etc).

The Franxx mecha (Strelitzia, Delphinium, Argentea, Genista, Chlorophytum) are all named after wild flowers.

Creator Atsushi Nishigori also worked as the lead character designer for the series Gurren Lagann

Yûichirô Umehara had to drop out of his role as Goro due to sudden health problems.

This is the second show Yûto Uemura has worked on where the characters are named after numbers; the first was Nanbaka (2016).