SIS (Soft Is Strong), the EP's title, reflects one of Katseye's core beliefs - Soft Is Strong - and also nods to the sisterhood they've forged, despite coming from immensely different cultures. The six members of Katseye are: DANIELA (USA); LARA (USA); MANON (Switzerland); MEGAN (USA); SOPHIA (Philippines); and YOONCHAE (South Korea). 

Contents include CD, Exclusive Photocard (2 random out of 6 exclusive photocards), Photocard (2 random out of 6 photocards), Lenticular Card, Lyric Card (5, for each song), Photobook, Stickers, Paper Key Ring, Polaroid, Postcard (6, of each member), Folded Poster.

1. Debut
2. Touch
3. My Way
4. I’m Pretty
5. Tonight I Might