空想メソロギヰ

"空想メソロギヰ" is a 2011 single by Yousei Teikoku and the OP 1 for the television anime Mirai Nikki (未来日記; The Future Diary), which was animated by asread. Lantis released it on November 9, 2011 as the band's 10th single, and the song later appeared on the album PAX VESANIA.

YUI wrote the lyrics, Tachibana Takaha composed the music, and Yousei Teikoku arranged the title track. The single also includes the B-side "missin'" and an instrumental version of "空想メソロギヰ".