Visions of Coleus takes place early in the second season of the TV show That Time I Got Reincarnated as a Slime, and is based on a four-part series of novellas that were included on the Blu-Rays of the show’s second season. This whole scene occurs prior to Rimuru’s elevation to True Demon Lord, that is, prior to Tempest’s attack and the 20,000 men that were massacred in retaliation. This indicates that although Rimuru is still strong at this point, he is not the unstoppable force he will ultimately become.
To be honest, it’s nice to see you back. In a fair fight, Rimuru would not be able to defeat some of the powers in this novel, and there are other forces that would test the limitations of Rimuru and his comrades. Because Rimuru must rely on cunning and deception rather than brute force to solve the mystery of what’s happening in the Kingdom of Coleus, there is a good deal of tension in the narrative.
The way this ONA gently compels Rimuru to recognize his history in a way he hasn’t since reincarnating in the fantasy world is its strongest feature. He chooses Satoru—that is, his name from his former life—as his identity for this covert operation because it is the only other name he is certain to reply to. He later encounters Princess Zenobia, who possesses the ability to sense a person’s soul form. In Rimuru’s instance, she sees the man he was prior to his death on Earth, even though this mostly enables her to determine if someone is good or bad. As such, he decides to adopt an idealized appearance of himself rather than Shizu when he transforms into the “Great Phantom Thief Satoru” in order to fulfill his purpose. He’s back in his former body for the first time in years, and he’s still trying to help others the way he always did.
The smaller cast is particularly advantageous for this ONA. The plot mostly centers on Rimuru and a new cast of people, while Souei and Benimaru make an appearance in the last act. We are rewarded with a considerably tighter tale, albeit one that has certain inherent problems, as we are spared from having to give every member of the TV anime’s large cast their due.
Even though the overall plot is very simple to follow, many viewers won’t comprehend all of this ONA. This is because, at its core, this ONA feels more intended for readers of the original novels than for viewers of the TV anime. Violet and Luminous Valentine will play important roles in future events. By the time the last credits roll, viewers who have just watched anime will not have the context provided by knowing their objectives and motivations, which can make the tale feel strangely underexplained.
Furthermore, the plot was confined by the presence of both Violet and Luminous Valentine. By the time Rimuru meets both characters for the first time, it is already decided. They cannot thus meet in this ONA, and the novel employs a number of handy devices to make sure they do not. When all it amounts to is Rimuru, Souei, and Benimaru quietly waiting behind an opaque bubble (which Rimuru can easily escape) for several minutes with nothing to occupy them save a corpse, while Luminous Valentine and Violet engage in combat, it feels more than a little contrived.
Overall, Visions of Coleus is a passable little side tale from That Time I Got Reincarnated as a Slime. This flashback to an earlier period in the larger tale offers a decent mystery with plenty of twists and turns, however readers of novels will benefit from it more than viewers of anime alone. There’s no excuse not to check this out if you’re already involved in That Time I Got Reincarnated as a Slime.