Warning! Spoilers ahead for PPPPPP chapter 12!
Lucky Sonoda's ability to grant wishes through his piano playing in Shonen Jump's PPPPPP just caused him to inadvertently make his estranged brother Reijiro Otogami depend on the effects of his music like a drug. Known as experiential-visual music, only the most talented musicians or those who have had unique experiences can create illusions or apparitions through the power of song - and Reijiro enjoyed Lucky's far too much.
As revealed in an earlier chapter, Reijiro's father who's a renowned legendary pianist separated Reijiro and his five other children from the regular world to hone their own natural talents in a musical conservatory. Reijiro suffered from his isolation. Reijiro's father had already kicked Lucky out of the family for his incompetence, and Lucky had been the only one of Reijiro's siblings with whom he connected. Meanwhile, the only friend he made at the conservatory named Saibo soon came to resent his abilities to the point where he actually tried to harm him, isolating him more. But Lucky's piano playing just allowed Reijiro to experience what it would feel like to go home with his friend Saiba. Reijiro enjoyed it so much that he recently requested that Lucky play for him every day so that he could live in his dream forever and escape reality, as revealed in chapter 12 of PPPPPP by mangaka Mapollo 3.
This is a massive moment in the manga for a number of reasons. The concept of losing oneself in a dream that may never come true is quite dark, especially since Reijiro would be using his brother's piano playing like a drug rather than trying to make his wish a reality. But what's more crucial is the understanding that PPPPPP is positioning Lucky to undergo equally as intense reunions with his other five siblings whom he hasn't seen since their father abandoned him. All of his siblings are renowned up-and-coming piano legends known as the Otogami sextuplets (not septuplets since their father ensured the world didn't know of Lucky's existence due to his failure at music). And since Lucky is pursuing piano playing to one day compose music with his siblings again, he is destined to compete against them.
Each of Lucky's upcoming competitions against his siblings is expected to be just as emotional as the rivalry against Reijiro. Even though Lucky always meant the world to Reijiro, Reijiro originally treated Lucky with contempt during their initial reunion after years of estrangement when he learned that Lucky still wanted to pursue piano. Of course, this distasteful reaction is undoubtedly the result of Reijiro being subjected to his father's negativity for years, but all of that nastiness washes away after he experiences Lucky's almost psychotic-inducing playing.
While Reijiro's desire to use Lucky's playing like a drug is compellingly dark, there's still a mystery involving his own form of experiential-visual music that PPPPPP has yet to solve. Reijiro can summon giants similar to the eponymous monsters in Attack on Titan, but readers still don't know what Reijiro's titans represent and why he summons them in the first place. Regardless, it's unlikely that Lucky's other siblings will have a similar reaction to their brother's playing like Reijiro did where they plead him to play for them every day. Hopefully, this series won't fall victim to Shonen Jump's proclivity to ax titles prematurely so fans can see how it plays out.