DESTINY+ requires a high-performance kick stage with a high mass ratio and high launch system safety. The kick stage requires a reliable laser ignition system, which is the subject of this study. Our development efforts included componentizing and dual redundancy elements, such as capacitors and laser diodes in the laser firing unit, which is designated LUUS. LUUS has two types of laser-initiated devices for motor ignition and separation device operation. An optical fiber path also enables a continuity check by an optical frequency domain reflectometry device. Further, we conducted continuity checks and laser ignition tests to validate the design in procedures simulating assembly- and launch-site operations. These tests successfully executed inspections and ignitions as planned. These results confirm the validity of our design, bringing us closer to realizing a reliable laser ignition system for launch operations applicable to DESTINY+. This contribution paves the way for future advances in high-performance, safe launch systems for solid rockets in space exploration.