Part I. The Search for Continuous Gravitational Waves; Part II. Exploring the Neutron Star Zoo; Part III. Observations of gravitational-wave afterglows Alessandra Corsi; GRB 170817A and the long-term aftermath of neutron star mergers Hendrik van Eerten; Kilonovae and short GRBs observations in the multi-messenger era Paolo D'Avanzo; Modeling kilonova emission from neutron star mergers Masaomi Tanaka; Multi-messenger science with Athena and future multi-messenger observatories Luigi Piro; Part IV. Physics in Ultra-Strong Magnetic Fields Alice Harding; Magnetic field evolution in the crust of neutron stars; Part IV. Physics in Ultra-Strong Magnetic Fields Alice Harding; Magnetic field evolution in the crust of neutron stars; Part V. Search for gravitational-wave transients associated with magnetar bursts during the third Advanced LIGO and Advanced Virgo observing run Kara Merfeld; Inferring the dense nuclear matter equation of state with neutron star tides Pantelis Pnigouras; Constraining three-nucleon forces with multimessenger data Andrea Sabatucci; Modelling the deformability of magnetized neutron stars in the light of future continuous gravitational waves detection Niccolo Bucciantini; Prospects for studying Galactic neutron stars in binaries with LISA Valeriya Korol; Gravitational-wave EM Counterpart Korean Observatory (GECKO) Myungshin Im; The neutron star neutron star merger GW170817; part Korean Observatory (GECKO) Myungshin Im; The neutron star neutron star merger GW170817; Part VI. INTEGRAL contributions to magnetars and multimessenger astrophysics Sandro Mereghetti; PULXs as accreting magnetars.