(This is a cover of an existing song, transcribed by ear and recreated using the soundfont of Dungeons and Dragons: Shadow Over Mystara)

The game's full title is a bit of a mouthful, and I don't think "Shiren the Wanderer: The Tower of Fortune and the Dice of Fate - Tower of the Future 2nd part (Dungeons and Dragons: Shadow Over Mystara soundfont)" was gonna fit in there.

Funny story though - while playing through the main story of Shiren 5 I was almost certain the soundtrack was still from Koichi Sugiyama like the first two games, but it turns out a new guy's been composing for the series since the Wii game, Hayato Matsuo. He apparently worked under Sugiyama arranging his songs for stuff like the DS ports of Shiren 1 and Dragon Quest 4 thru 6, and I think it's safe to assume he picked up some elements of Sugiyama's style.

This track in particular seems to call to mind part of Table Mountain from Shiren 1, as it's got that same kind of dark and lonesome feel, but the specific way it iterates on the track you hear in the first part of the Tower of the Future makes it sound like you're going down deep into some isolated underground domain, not climbing up the floors of a tower.
This has been Overanalyzing Unremarkable Music from Unremarkable Games, see you next song!