Tanshin, sometimes translated as "Lone Wolf" or as fighting solo, is a term unique to Tenchi Academy's Hoshitori system. It is pronounced identically to 単身 (tanshin), "unaided," but written as 単刀 (tanshin), "lone sword." It refers to the state of being without a shinyuu, or to a particular swordbearer in this state.

Tanshin status is highly undesirable. In addition to the inherent disadvantage in fighting alone against teams of two, duelling victories won by a student without a registered shinyuu are considered invalid, and do not count toward her star or point totals. Conversely, any losses incurred will be reflected in her totals. Thus a tanshin's rank cannot go up, only down.

Solo students are nonetheless expected to participate in the Hoshitori whenever the bell rings. If they do not remain within designated duelling areas, or if they disable the sensors on their stars, they will (after a certain period of time) begin to automatically forfeit points. However, so long as they observe these two proscriptions, they are under no obligation to actively seek out or engage in duels. Hiding or fleeing are permitted strategies, and will often prove necessary, as unaided students are easy, attractive targets for shinyuu pairs.