Time Trip App sends a high school teacher and her students back to 1868, when the shogunate is collapsing and a battle over Edo appears imminent. There they encounter Katsu Kaishu, a samurai trying to prevent the city from being consumed by war.
Although the film uses time travel and comedy, its most memorable idea is surprisingly serious. Katsu understands that fighting fellow Japanese people will only create unnecessary suffering. His goal is not to prove his courage on the battlefield but to find a way for Edo to survive without a devastating confrontation.
The image of a samurai fighting while keeping his sword in its scabbard captures that attitude perfectly. It recalls the ideal of a warrior who possesses strength but refuses to kill when killing is unnecessary. The scene may even bring Himura Kenshin to mind, but Katsu’s restraint is connected to a larger political purpose: preventing bloodshed rather than simply defeating an opponent.
Katsu Kaishu is remembered historically for helping negotiate the bloodless surrender of Edo Castle. The film turns that achievement into the center of its story, presenting peace not as weakness or surrender, but as a difficult victory requiring judgment and courage.
Time Trip App therefore works as more than a playful visit to the end of the Edo period. Its most appealing character is a samurai who recognizes that the finest outcome is not always winning a war. Sometimes the greater achievement is making sure the war never begins.