Both Tokimeki and Ririka SOS were turned into light novel series published under Shueisha's Cobalt Pinky imprint. They are all out of print.
Ranze arc novelizations
Five-volume series published between 1993 and 1994 and featuring both new and old color art on the covers and frontispieces. Ikeno also drew black and white art to illustrate the text.
Ririka SOS novelizations
Three-volume series published between 1995 and 1996 featuring new art by Ikeno on the covers. The inside pages are illustrated with anime art.
Thank you to hotwaterandmilk for the above scans!