For the most part Jap weapons sucked but when they did it right they had a winner. The knee mortar for one, it was devastating. Nip 18 inch naval guns were shockingly powerful.
Those powerful guns were undone by poor gunnery control. Ziggy Sprague commented during the battle on how poor the Japanese gunnery was at Samar.
For the most part Jap weapons sucked
Sub skippers complained to Washington and were basically told to ‘git gud.’ Eventually a demonstration convinced some pencil pusher and the problem was resolved.