Daisuke Aramaki commands Public Security Section 9 as its Chief, holding the rank of Lieutenant Colonel from the Japan Ground Self-Defense Force. His leadership focuses on high-level strategy and leveraging deep political connections to shield and empower his team, avoiding direct field operations. Aramaki demonstrates fierce loyalty to Section 9, repeatedly risking his career to protect them from governmental threats. This included defying the Prime Minister’s orders to launch an unauthorized raid on exiled dictator Ka Rum’s residence during the Solid State Society incident. Informally likened to an "old ape" by subordinates due to distinct facial features, his appearance belies a shrewd, diplomatic mind adept at navigating complex bureaucracies.

Aramaki possesses minimal cybernetic augmentation, limited to a cyberbrain implant for network interfacing. This contrasts with his more extensively modified team and reflects his role as a stabilizing human element. His background includes estrangement from his mentor, Colonel Tonoda, whom he helped imprison for undisclosed misconduct prior to the events of Stand Alone Complex. He has experienced multiple marriages, has children and grandchildren, and maintains a disconnected relationship with his brother, Yousuke Aramaki, who aided refugees during the Dejima crisis in 2nd Gig.

Throughout Section 9’s investigations—spanning the Laughing Man case, Individual Eleven, and Solid State Society—Aramaki functions as a crucial political counterweight. He reinstated the unit after its dissolution by negotiating directly with Prime Minister Yoko Kayabuki, showcasing his influence. His tactical acumen emerges during crises, coordinating responses to Puppeteer-linked child abductions and neutralizing threats like Cabinet Intelligence Service head Kazundo Gouda. Aramaki sustains vital alliances, such as with military intelligence officer Kubota, to secure Section 9's operational autonomy.