A Very Safe Supplement

A Safe Drug is the twelfth chapter of the Owari no Seraph manga.

Short Summary
Yuichiro and his friends make their way to Shinjuku in time for the city's defense against vampires. Meanwhile, Glen identifies the invasion force's leader, Felid Bathory, and proceeds to eliminate him with his forces. He fails to eliminate Felid, and is instead brought to a brawl with Mikaela Hyakuya.

As Yuichiro and his friends make their way to assist Glen, Shinoa reminds them of using a drug that could help them increase their strength to fight vampires, but warns that an overdose could kill them when they use the drug. Amidst the ensuing struggle, Glen was overpowered by Mikaela and Felid (who interfered and gave a fatal blow to Glen), and as he was about to take in another drug which could kill him, Mika thrusts his sword at Glen. Immediately afterwards, Yuu saw the situation and charges at Mika with his sword, but at that moment both Yuu and Mika recognized each other's faces.