Rhapsodia is the Japanese name for Suikoden Tactics. It's definitely from the Suikoden series, as it uses characters and places from Suikoden 4, and the runes and elemental magics play a role. I don't know the reasoning behind calling it Rhapsodia in Japan.
Gamespot has some information about Suikoden 5 here
. Given the poor reception Suikoden 4 got in both the US and Japan, I'd imagine Suikoden 5 will be quite different than 4. Then again, they are basing Tactics on 4, so who knows?