For Serani Poji, the game's credits list Fukutomi and Tomoko Sasaki (
https://vgmdb.net/artist/1467) as Producer and Co-producer respectively.
I usually see Sasaki credited as the primary composer behind Serani Poji, including the three tracks on this album (
e.g. the Sega Retro wiki), but I can't find a primary source on that. Also worth noting that "Serani Poji" continued to release albums long after Roommania, and most sources I've read say Sasaki was the sole composer after the album "one-room survival."
It seems safe to assume Sasaki was the composer for these tracks, but maybe Fukutomi and Sasaki should both be credited just to be safe...