Pee, thank you for observation or Russian press. There is really a huge enthusiasm about this route here, in Saint Petersburg.
Only few days of sale behind, but almost all starting promotional fares (12 euros one way) for April and May flights are gone. The price of the very first flight LPP - NRN at 1st of April is already 55.47 euros, return flight at April, 4 is 51.06 euros.
Taxes and fees from Lappeenranta are 20.48 euroes per person and the are similar for the ones in Tampere.