Unser Debut + Sechs

In Japan, the albums "Unser Debut" and "Sechs" were released together as a double-album (triple album so to speak) in gatefold cover including three info sheets including song texts and with Obi.

The front cover lists this as "Unser Debut (4)" and there is a line on the front cover "Wie geht es Dir jetzt" (in Japanese).
The spine and labels list "Unser Debut" as a title only.

The "(4)" refers to a continuation of numbers hidden on earlier vinyl releases of Die Tödliche Doris. The question "Wie geht es dir jetzt" (how are you right now) is answered on the follow-up/companion album Sechs (there: "Jetzt ist alles gut" (in Japanese) - now everything is fine).

This is actually the first part of "Die 5. Unsichtbare LP". The second part is the LP Sechs.
On both LPs the individual tracks feature the exact same length. Both albums (well, all three to be exact) were conceptualized at the same time, but recorded at different locations and at different times. All compositions, lyrics, titles complement each other, but can also be listened to and enjoyed on their own. If you play both records at the same time you will hear "Die 5. Unsichtbare LP" ("The 5. Invisible LP").
Also the artwork of both releases correspond with each other, each features hints and elements that were picked up on the later release.

Later the "Unsichtbare 5. LP" was materialized, first as a CD in 1993 as Die Unsichtbare 5. LP Materialisiert Als CD / The Invisible 5th LP Materialized As CD and in 2015 on vinyl as Die Unsichtbare LP.