We present scientific and technical justifications of a potential coordinated Euclid/CSST/JPCam/JUST survey of the Euclid Deep Field North (EDF-N), aimed at probing the multi-phase circumgalactic and intergalactic medium (CGM/IGM) at the cosmic noon over ∼20 deg2. The survey is structured around three connected goals: (1) improving photometric redshift (photo-z) accuracy through the combination of broad- and narrow-band photometry, enabling reliable identification of large-scale structures; (2) probing extended CGM emission with dedicated narrow-band imaging; and (3) mapping foreground IGM via absorption-line spectroscopy of background galaxies. Together, these components establish an integrated observational framework to investigate galactic ecosystems—linking galaxies to their circumgalactic and intergalactic environments—at cosmic noon. We show that the J-PAS-like narrow-band system used in JPCam substantially improves photo-z accuracies from only the Euclid/CSST broad-band data, especially for star-forming galaxies at z ∼ 1.0–1.4. This enables the identification of galaxy groups and (proto-)clusters directly from photo-z measurements. Stacked JPCam narrow-band imaging should also detect extended [O ii]-emitting CGM halos. We then construct mock three-dimensional (3D) gas distribution model and realistic galaxy catalog, and further construct mock CSST and JUST background galaxy spectra adding Lyα and Mg ii absorptions. The reconstructed 3D H i field from CSST Lyα forest reliably recovers large-scale structures; however, our simulations indicate that detecting diffuse IGM Mg ii absorption with JUST is infeasible, either through spectral stacking or via the two-point correlation function method. We conclude that constraining the metallicity of the diffuse IGM will require significantly deeper and higher-resolution spectroscopy expected from future facilities such as the 39 m E-ELT.