Chibi Chibi Lain: The Empire Strikes Back (ちびちびレイン 帝国の逆襲)
Six silly 4-koma strips. Five shipped in the Japanese home video liners (strip #2 was dropped and joked about as a 'deleted scene'). All six are in the 1999 art book; the five plus two new colour strips are in the 2010 Blu-ray RESTORE booklet.
Sources: lain.wiki archived · lawmune.net archived · ja.wikipedia.org archived