Kamen Rider Build 38

Episode 38; Mad World; マッドな世界
	Kamen Rider Build episode
Writer	Muto Shogo
Director	Yamaguchi Kyouhei
Action Director	Miyazaki Takeshi
Original air date	June 3, 2018
Viewership	2.6%
Forum Thread	Thread
Fan Rating	4.7 / 5
Episode chronology
← Previous; Episode 37; The Ultimate Phase	Next →; Episode 39; Unstoppable Genius
	Episode List

Kamen Rider Build
< Ep 37	Mad World マッドな世界	Ep 39 >
Aired with Lupin VS Pat 17

Important things that happened

The woman play in the piano is Nakamura Yayoi, who has a series of albums called Music Therapy. Here is her blog post talking about her appearance on the episode.
No opening sequence, the music is instead used at the end.