"Last Kingdom" is a driving instrumental track by USAO (Masaharu Kubota), a prolific Japanese electronic music producer known for his hard-hitting, genre-blending style across SEGA's rhythm game ecosystem. Clocking in at 150 BPM and running 2 minutes and 23 seconds, the song deploys USAO's signature punchy synth leads, aggressive basslines, and rapid-fire percussion, the kind of uncompromising energy that suits a high-level challenge chart. The track first appeared in ONGEKI SUMMER PLUS before spreading to CHUNITHM NEW PLUS and eventually landing in maimai DX FESTiVAL PLUS on September 1, 2023. In maimai, it was introduced as part of the ONGEKI Area 6 (オンゲキちほー6) crossover event, continuing a tradition of importing standout boss songs from SEGA's sister rhythm games. The song carries no lyrics, it is a pure instrumental designed to drive gameplay intensity. The maimai chart lineup spans Basic (level 4) to Master (level 13+). The Expert chart, designed by サファ太 (Safata), and the Master chart, designed by Luxizhel, both leverage the full range of DX note types, Tap, Hold, Slide, Touch, and Break, to create patterns that mirror the track's relentless momentum. The Master chart's 13.8 constant places it among the upper tier of FESTiVAL PLUS content, demanding precise slide coordination and rapid fingerwork.