  Recent supernova searches revealed a number of fast-evolving luminous
transients. We perform radiation hydrodynamic simulations of light curves of
several models of supernova from super--asymptotic giant branch (super-AGB,
SAGB) stars with low mass envelopes ($M_{\rm env}$ $\sim$ $0.05-1.25$
$M_{\odot}$). The differences in the light curves found among the models are
used to link the observed events to the most appropriate models. In particular,
we propose that KSN 2015K is an electron-capture supernova. We assume
"optically" thick CSM around SAGB and the circumstellar interaction powers the
peak luminosity of the light curve with a short rise time. The faint tail might
be influenced by the spin-down luminosity of a newborn Crab-like pulsar. Our
fits indicate an ejecta mass of $0.02-0.05$ $M_{\odot}$, a circumstellar medium
(CSM) mass of $0.10-0.12$ $M_{\odot}$, a radius of the CSM photosphere $\sim$
10$^{14}$ cm, a kinetic energy of $\sim$ 3 $\times$ 10$^{50}$ erg, a
photospheric velocity $v_{\rm ph} \gtrsim 10,000$ km s$^{-1}$ and a pulsar
total spin energy ($2.5-4$) $\times$ 10$^{49}$ erg.
