Shamrock is one of Tsubaki's subclass.
Shamrock is a tall man, dressed properly in a white suit. He has slicked back blonde hair and dark red eyes due to him being a vampire. He has a jaggedly cut black eyepatch over his right eye.
He then appears during the festival, suddenly asking Mahiru to deliver a silver briefcase he 'found' to the lost and found department. It is then revealed after a bomb explodes in the festival that he is the one who planted them.
In chapter 50, Shamrock is seen sitting in a cell confined within C3. Two other prisoners, revealed to be Gil and Ray, begin to talk to Shamrock, who is resistant. Shamrock ignores them until he is asked if he is Melancholy's subclass. This catches his attention and he begins to pay attention to the conversation.
Gil gives Shamrock information from a "certain source" saying that Shamrock will be disposed of in a few days. Gil proposes that once this time comes, Shamrock should join the two of them. Shamrock asks who they are and Gil replies that they just have a woman they want to protect.
Later, while C3 is collapsing, Shamrock makes his way to a control room on the third floor. He makes contact with Higan and tells him the building will collapse, to tell Otogiri and Berukia to escape, and relay to Tsubaki that the "concentration is probably already dense enough." Higan asks what he should do once Otogiri and Berukia escape and Shamrock says he will go with him to destroy the building per Tsubaki's instructions.
Then Shuhei enters and shoots at Shamrock, breaking the communication device. Shuhei then identifies Shamrock as a former member of C3 due to his knowledge of the system. Shamrock then begins laughing and tells Shuhei that he looks just like his father, who he killed. Shamrock thanks Tsubaki for the opportunity to kill his dear friend, Shuhei's father, once again with his own hands. Shuhei declares he will kill Shamrock.
Shuhei then uses the spell Four and Twenty Blackbirds, Nobody in the Rye and attacks Shamrock, however, Shamrock dodges and pulls a gun similar to C3's magic weapons. Shamrock dodges another of Shuhei's attacks and retaliates, but Shuhei blocks using his spell. During the battle that ensues, Shuhei reveals that when Shamrock was human and part of C3, he was the hope of C3's German branch. Shamrock tells him that he was transferred from the German branch to the Tokyo one and was put on the same team as Yoshimasa, Shuhei's father.
After Shamrock compares Shuhei to his father, Shuhei gets angry and yells that he's not his father and then asks Shamrock why he killed him. Shamrock responds with the statement that if Shuhei doesn't intend to forgive him, then there's no point in explaining his reasons. Shuhei agrees and launches an attack that hits Shamrock multiple times, but Shamrock gets back up looking no worse for wear and appears right in front of Shuhei and proceeds to ask about Shuhei's hair color and then insult his appearance. Immediately after, he bites Shuhei on the shoulder and then states that tastes the same as his father. Shamrock then uses the spell Die Verwandlung, the Nighthawk Star, which causes several long spider-like appendages to emerge from his back. Which he uses to attack Shuhei, who, though he manages to dodge the first attack and is only knocked onto his back, is ultimately unable to dodge fast enough despite his increased vision and is hit in the shoulder and appears to be defeated.
Shamrock then sits down on a large piece of rubble and starts talking to Shuhei about his first encounter with Tsubaki. It had happened 17 years previously when Yoshimasa, Shamrock, and a bunch of others went out to capture Tsubaki. When they found him, they realized that he was much stronger than they had thought and were forced to retreat. While fighting on the front lines to help cover their retreat, Shamrock thought that since Yoshimasa had a young son and another child on the way, that he couldn't let him die there. However, when Shamrock turned to tell him to leave, there wasn't anyone there and he realized that everyone, including Yoshimasa, had left him behind as a decoy. This causes Shamrock to start thinking thoughts about their friendship and asking if it had all just been to acquire a pawn and if Yoshimasa had always intended to betray him in the end. Instead of killing him, Tsubaki pauses a few feet from him and comments that it was terrible and a heartless thing for them to do to Shamrock. He starts talking to Shamrock about reasons for various things and then empathizes with him. Shamrock lifts his gun and proceeds to shoot himself in the head, Tsubaki is surprised and then saddened and says, "Come with me. I will give you a new name." and it is assumed that that is when he turns Shamrock into his subclass and gives him the new name Shamrock.
He seems to be a formal man and in some appearances in the manga he talks in old terms like "cometh" and "thy". He revers Tsubaki.
He distrusts Sakuya and believes he will betray them eventually.
- "But when...doth the liar commit suicide? A dangerous lad is he..." (Chapter 10, about Sakuya)
- "Young Master!! Did you see that?! Did you?! Our funeral service...is open for business!!" (Chapter 11)
- "To think...that I could kill my dear friend by my own hands once again...!!" (Chapter 57)
- He was voted very lowly in the servamp favorite characters poll.
- He always suggests that Sakuya should commit harakiri.
- He seems to be angered about the fact that Higan is No. 2 in Tsubaki's team and not himself.
- In chapter 62, it is shown in a flashback that his eye was hurt during a battle with Tsubaki 17 years ago and it is assumed that that is when he started wearing an eyepatch.
- According to the fan book, he is originally from Germany.
- Also according to the fan book, his outward appearance is ranked 7.
- He was originally part of C3's German branch before being transferred to the Tokyo branch