On multiple occasions, Seigi's tattoo is described as "triggerless" (this is the wording used on Crunchyroll). The first time we hear this is near the end of episode 1, around 22:08. However, when Seigi is talking with Izzy and Tom on the school roof in episode 2, Izzy tells him that his tattoo is triggered by blood.
It hardly makes sense for a "triggerless" tattoo to have a trigger. What's the deal?
(At first glance, this seems like a translation mishap, since the Japanese word in question is mugen, and I don't know of any way to get from there to "triggerless". But perhaps there's a good reason for this - I've only seen 3 episodes of the anime to this point, so I'm not very knowledgable about Taboo Tattoo.)