A female in her late 50s experienced dyspnea and was transported by an ambulance. Her hemoglobin score was low, and CT imaging showed a giant tumor in her stomach. The tumor perforated her liver and invaded the abdominal wall and duodenum around the Treitz ligament. She required surgery because of the massive hemorrhage due to the tumor. Total gastrectomy with lateral segmentectomy of the liver and resection of the duodenum and the ileum around the Treitz ligament were performed. At 1.5 months after surgery, chemotherapy for malignant lymphoma was successfully initiated.