| Elemental Knight & Open Battle|
|Publisher||Yen Press (JP)|
|Magazine Issue||Monthly Dragon Age June 2015|
|Release Date||May 9, 2015|
Elemental Knight & Open Battle is the fifty-fourth chapter of the Trinity Seven manga series, released on May 9, 2015 in Monthly Dragon Age Junde 2015 issue and later compiled in the twelfth volume on August 8, 2015.
As Anastasia-L's Demon Lord Knights appear, Mira is still shocked about Arata who Ana introduces as her Superbia Knight Astral Trinity. Astral states that Arata is no longer present, however Lilith refuses to accept and prepares for battle.Meanwhile, Abyss Trinity remarks that Astral is probably the Demon Lord Element in a physical form, to the suprise of Lieselotte. Abyss further reveals that Demon Lords whose world has been destroyed eventually arrive to the world of Demise, however, Ana, the Saint of Resurrection, can will the Element to transform into her knight. The Demon Lord notes that the Saint was the result of his actions, sending his daughter from his world.
Ana begins the match by sending her two other knights, which Lilith attempts to counter but her bullets does not not have any effect on them. However, as the knights are about to strike, MIra unleases her magic to damage them greatly. Ana is impressed that she was able to determine her knight's Archives while Arsha comments the Trinity Seven are quite troublesome. Mira next summons multiple Arias to further injure the knights before Lilith performs the final strike to eliminate them. However, Astral manages to block her magic in order to protect Anastasia and Arsha.
Observing the match, Lieselotte and Selina comments that in order to defeat one Demon Lord Knight, they had to cast one of Logos Art's greatest spells. However, Lilith and Mira managed to defeat two at the same time. But the Headmaster notes that the two used a large amount of magic for their last onslaught while the opposing team remains unharmed with Astral still present. Lieselotte agrees, but hopes that certain people can help with Arata's situation.
- Continuing from the previous chapter, Lilith and Mira's match against Anastasia-L and Arsha began with Ana summoning three of her Demon Lord Knights, including Astral Trinity.
- Astral states that Arata is no longer present and that he is Ana's Demon Lord Knight. Arata was originially captured by Anastasia and became Astral in Logos Mystery & Lost Master.
- Abyss states that his act of sending his daughter Lilith to the present world was the cause of Ana's transformation as the Saint of Resurrection, which was recounted in Saint Terminus & Demon Knight.
- Lieselotte and Selina both note, in comparison to Lilith and Mira, that in order to defeat even one Demon Lord Knight, they had to use one of Logos Art's strongest spells. This is a reference to their battle against a Knight during the Underground Magical Research Showdown which concluded in Chapter 47.
- Arin and Hijiri find themselves in the world of the Breakdown Phenomenon with the goal of rescuing Arata from his imprisonment. Originally, they had intentionally caused a Breakdown Phenomenon during their match with Yui and Lugh in the previous chapter, which resulted in the two disappearing.