  TOI-2525 is a K-type star with an estimated mass of M =
0.849$_{-0.033}^{+0.024}$ M$_\odot$ and radius of R = 0.785$_{-0.007}^{+0.007}$
R$_\odot$ observed by the TESS mission in 22 sectors (within sectors 1 and 39).
The TESS light curves yield significant transit events of two companions, which
show strong transit timing variations (TTVs) with a semi-amplitude of a $\sim$6
hours. We performed TTV dynamical, and photo-dynamical light curve analysis of
the TESS data, combined with radial velocity (RV) measurements from FEROS and
PFS, and we confirmed the planetary nature of these companions. The TOI-2525
system consists of a transiting pair of planets comparable to Neptune and
Jupiter with estimated dynamical masses of $m_{\rm b}$ =
0.088$_{-0.004}^{+0.005}$ M$_{\rm Jup.}$, and $m_{\rm c}$ =
0.709$_{-0.033}^{+0.034}$ M$_{\rm Jup.}$, radius of $r_b$ =
0.88$_{-0.02}^{+0.02}$ R$_{\rm Jup.}$ and $r_c$ = 0.98$_{-0.02}^{+0.02}$
R$_{\rm Jup.}$, and with orbital periods of $P_{\rm b}$ =
23.288$_{-0.002}^{+0.001}$ days and $P_{\rm c}$ = 49.260$_{-0.001}^{+0.001}$
days for the inner and the outer planet, respectively. The period ratio is
close to the 2:1 period commensurability, but the dynamical simulations of the
system suggest that it is outside the mean motion resonance (MMR) dynamical
configuration. TOI-2525 b is among the lowest density Neptune-mass planets
known to date, with an estimated median density of $\rho_{\rm b}$ =
0.174$_{-0.015}^{+0.016}$ g\,cm$^{-3}$. The TOI-2525 system is very similar to
the other K-dwarf systems discovered by TESS, TOI-2202 and TOI-216, which are
composed of almost identical K-dwarf primary and two warm giant planets near
the 2:1 MMR.
