Hot-spring Adventures

What if there was a different result in the Onsen stay (see the KHR OVA)? The Ten-Year Bazooka sent the to-be-Decimo of Vongola, Sawada Tsunayoshi, into the future and the TYL Tsuna into the present. But due to the water fight between the Varia and Vongola boy's, instead of the usual 5 minutes, they have to stay in th...