Voiced by: Kousuke Okano (Japanese, visual novel), Takahiro Sakurai (Japanese, OVA), Miyu Irino (Japanese, TV anime), Keith Silverstein (English, OVA), Newton Pittman (English, TV anime)
- Anti-Hero: Though he is fully aware of the consequences and misdeeds of his actions.
- Badass in a Nice Suit: During his time as an assassin he's commonly dressed in finely-tailored dark suits.
- Bad "Bad Acting": A rare funny moment comes in episode 4 when, after Ein and Zwei spend a day posing as vacationing sweethearts while scouting out their next target, she has this to say about his atempts to act casual:
- My God, What Have I Done?:
- After he accidentally shoots Ein while trying to kill Scythe Master. Made even worse by the fact that the entire time he was trying to SAVE HER LIFE. And lets not forget those flashbacks we get to when they're trying to escape and he promises that, one day, he'll make her laugh again.
- Zwei gets this AGAIN after realizing, that it's his fault Cal got into being an assassin.
Voiced by: Omi Minami (Japanese, visual novel & OVA), Ayahi Takagaki (Japanese, TV anime), Mela Lee (English, OVA), Lindsay Seidel (English, TV anime)
- Brainwashed: Scythe does this to her to keep her loyal. After Claudia's coup d'etat, the process is ceased and reversed on the agents they still have. Scythe himself later decides that not brainwashing his subordinates may actually make them stronger.
- Innocent Fanservice Girl: Ein doesn't care about walking around naked in front of Zwei after having a shower.
- Sexy Backless Outfit: Ein's party costume in episode 6 and the dresses of the Zahlen Schwestern, both in the recent anime and in the visual novel.
Voiced by: Satomi Koorogi (Japanese, visual novel), Miyuki Sawashiro (Japanese, TV anime), Brittney Karbowski (English, TV anime)
Claudia Mc Cunnen
Voiced by: Kikuko Inoue (Japanese, visual novel & OVA), Aya Hisakawa (Japanese, TV anime), Cindy Robinson (English, OVA), Colleen Clinkenbeard (English, TV anime)
Voiced by: Ken Narita (Japanese, visual novel), Kazuhiro Nakata (Japanese, OVA), Isshin Chiba (Japanese, TV anime), Dave Mallow (English, OVA), Kent Williams (English, TV anime)
- Dub Name Change: The English Dub of the OVA switches his name around, changing it to "Master Scythe."
- Four Eyes, Zero Soul: The TV series and subsequent remake gave him glasses.
- Non-Action Big Bad: Despite overseeing and monopolizing on the creation of assassins, Scythe Master himself has no combat skills and relies on his minions even in his final showdown with Ein, where he even throws away his own weapon instead of trying to fight her.
Voiced by: Ai Orikasa (Japanese, visual novel & OVA), Akeno Watanabe (Japanese, TV anime), Megan Hollingshead (English, OVA), Shay Moore (English, TV anime)