Kokuminteki Idol ni Natta Osananajimi ga, Boro Apart ni Sunderu Ore no Tonari ni Hikkoshite Kita Ken

My childhood friend, who went away 3 years ago, is now performing on TV as a popular idol. And then I found out that the person who just moved into the room next to mine is the childhood friend herself, even as I'm watching her show! (Source: Kadokawa, translated)