- The name of this card "Onimaru" is a reference to "Onimaru Kunitsuna" (鬼丸国綱), a famous sword used by Hojo clan in Kamakura period of Japan.
- This card is the first Level 12 Synchro Monster that can be Synchro Summoned by using generic Synchro Materials, including only 1 non-Tuner monster.
- This card is the first Synchro Monster that has a "Only once per Duel" effect.
- This monster appears in the artwork of "Black Feather Reversal".
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