This paper presents a detailed anal. of supernova remnant (SNR) N103B located in the Large Magellanic Cloud (LMC), based on Suzaku and Chandra observations. The spectrum of the entire remnant was closely reproduced using three interstellar medium (ISM) components with temperatures of ∼0.32, ∼0.56, and ∼0.92 keV and one ejecta component with a temperature of ∼3.96 keV, based on spectral anal. of the Suzaku/X-ray Imaging Spectrometer (XIS) data. The ejecta was overabundant in heavy elements, such as Mg, Si, S, Ca, Fe, and Ni. The unprecedentedly high quality of data obtained by Suzaku/XIS, allowed us to correctly distinguish between the emissions from the ISM and the ejecta for the first time in a spectral anal. Combining spectral anal. based on Suzaku/XIS data with image anal. based on Chandra/Advanced CCD Imaging Spectrometer (ACIS) data, we verified that the ejecta distributions for elements from Si to Fe-K were similar to one another, although Fe-K emission was located slightly inward compared with that of lighter elements such as Si, S, Ar, and Ca. The onion-like structure of the ejecta was maintained after the supernova explosion. In addition, the ISM emission represented by O and Fe-L was located inside the ejecta emission. We compared hydrogen-rich ejecta plasma (called "H-dominated plasma"), which is indicative of Type II SNRs, with plasma rich in heavy elements and poor in hydrogen (called "pure metal plasma"), which is mainly observed in Type Ia SNRs. In the case of N103B, we could not determine whether the origin of the continuum emission in the 4.0-6.0 keV band was from ejecta (H-dominated plasma) or high-temperature ISM (pure metal plasma) only based on the spectral modeling of Suzaku/XIS data. High-energy continuum images in the 5.2-6.0 keV band obtained by Chandra/ACIS were extremely similar to those of ejecta, implying that the origin of the high-energy continuum might indeed be the ejecta. By combining spectral anal. with high-energy continuum images, we found some indications for H-dominated plasma, and as a result, that the progenitor of N103B might have been a Type II supernova. The progenitor mass was estimated to be 13 M☉ based on the abundance patterns of Mg, Fe, and Ni relative to Si.