I found the lyrics of Himitsukichi in this site. I found it hard to load the website so I will repost it here. [To the translator: Please message me if you want to take it down. Thank you.]

ヒミツキチ
Himitsukichi
Secret Base

artist: Maekawa Hiroki

Danball Senki TV Ending 2
written by Splash

Kanji:

どうしてうつむいているの? 僕で良けりゃ手を貸すよ
とっておきの場所がある 君だけに教えるよ

君の大事な物は何? ( Read more... )