The Welcome to the NHK opening (Puzzle by Round Table Feat) with Subs in Japanese and with German Lyric Subs.
Here are the whole Lyrics, if you want to sing it:
Sukoshi miageta sora dekisugita nichijou
Se wo mukeru tabi ni tsubuyaku dake
Doko ni ikeba ii no? Sonna kaoshiteru kimi to
Rojiura no kage tokei no hari ga
Tomatta jikan wo nurikaete
Sashinobeta ryoute kami awanai pazuru wo
Okizari ni shiteta futari deau made
Nakushiteta nani ka saigo no kakera wo torimodoshite
Arukidasou
Lyrics by animelyrics.com user "Rinian", thank you.