|“||Well, I'm surprised you have the guts to show yourself, but of course you brought Voids for insurance. You seem to think that all it takes to be like Gai is to wear a cloak, but you're not even coming close, you poser! And you never will!||„|
|~ Argo Tsukishima to Shu Ouma|
He is voiced by Anri Katsu in the Japanese version and Jarrod Greene in the English version, the latter of whom also voices Subaru Hidaka.
Despite supposedly being a teenager, Argo is a tall man, standing several inches taller than Shu and being at least as tall as Gai. He has spiky black hair, with a blonde streak in the middle. He is always seen wearing his Funeral Parlor uniform.
Argo has a hot-headed personality and becomes easily angered whenever someone insults or questions Gai's authority, showing that he is very loyal to him like most members of Funeral Parlor. Of all the members, he is initially the most disdainful of Shu due to his resentment of Gai, even forcing him to apologise when he calls Gai "selfish", stating that if he insults him, he's insulting everyone who believes in him as well. At one point, he even goes so far as to call Shu a "spoiled brat".
Like all Voids, Argo's Void (a black stick that shoots out black holes) reflects a hidden aspect of his personality i.e. the fact that he is a very gloomy person deep down, something that was initially unknown even to him. In general, however, Argo is rather grumpy, as he is almost never seen smiling.
Although he can be abrasive at times, Argo nevertheless has very strong moral standards; he is instantly disgusted by the ruthless dictator Shu has become and attempts to help Souta, who Shu had left to fend for himself underwater. He also refuses to submit to Shu, saying he would rather die than follow him, which results in him getting thrown in a cell. It's implied, however, that this is partially out of loyalty to Gai, as he later compares the two, asking Shu if he honestly thinks Voids alone makes him an effective leader. Nevertheless, he is horrified upon learning that someone's Void breaking causes them to die, to the point that he tries to convince Shu to stop using Voids, since the very thing he's using to try and save the students could ultimately be what kills them.
However, even with these standards, Argo is a pragmatist through and through; he always goes along with Gai's "needs of the many" style plans and is frustrated by Shu's inability to see the bigger picture, even being perfectly willing to die for Gai if the need arises. During the final battle, he also attempts to convince Ayase to leave Shu behind instead of attempting to rescue him, as he didn't want to risk losing both of them and was convinced there was little to no chance that Shu could survive, though against all odds he does.
Argo's void is a black stick that releases a light that brings forth darkness. Shu used his void in a mock-battle against Ayase and afterward, Argo realizes what a depressing person he is. After the mock-battle, Argo awakened and was informed of the event and states " A light the brings darkness...am I really gloomy guy deep down."
The fact that Shu is able to draw a void from Argo also suggests that he is 17 years of age or younger.